Harald's first day working at the Nielsen farm was more successful than he had dared to hope. Old Nielsen had a small workshop with enough equipment for Harald to repair just about anything. He had patched the water pump on a steam plough, welded a hinge on a caterpillar track, and found the short circuit that caused the farmhouse lights to fuse every night. He had eaten a hearty lunch of herrings and potatoes with the farmhands.

In the evening he had spent a couple of hours at the village tavern with Karl, the farmer's youngest son - although he had drunk only two small glasses of beer, remembering what a fool he had made of himself with liquor a week ago. Everyone was talking about Hitler's invasion of the Soviet Union. The news was bad. The Luftwaffe claimed to have destroyed 1,800 Soviet aircraft on the ground in lightning raids. In the tavern, everyone thought Moscow would fall before winter, except the local communist, and even he seemed worried.

Harald left early because Karen had said she might see him after dinner. He felt weary but pleased with himself as he walked back to the old monastery. When he entered the ruined building, he was astonished to find his brother in the church, staring at the derelict aircraft. "A Hornet Moth," Arne said. "The gentleman's aerial carriage."

"It's a wreck," Harald said.

"Not really. The undercarriage is a bit bent."

"How do you think it happened?"

"On landing. The back end of a Hornet tends to swing out of control, because the main wheels are too far forward. But the axle tubes aren't designed to withstand sideways pressure, so when you swerve violently they can buckle."

Arne looked terrible, Harald saw. Instead of his army uniform, he wore what seemed to be someone else's old clothes, a worn tweed jacket and faded corduroy trousers. He had shaved off his moustache, and a greasy cap covered his curly hair. In his hands he held a small, neat 35mm camera. There was a strained expression on his face instead of his usual insouciant smile. "What happened to you?" Harald said anxiously.

"I'm in trouble. Have you got anything to eat?"

"Not a thing. We can go to the tavern - "

"I can't show my face. I'm a wanted man." Arne tried a wry grin, but it finished up as a grimace. "Every policeman in Denmark has my description, and there are posters of me all over Copenhagen. I was chased by a cop all along the Stroget and only just got away."

"Are you in the Resistance?"

Arne hesitated, shrugged, then said, "Yes."

Harald was thrilled. He sat on the ledge he used as a bed and Arne sat next to him. Pinetop the cat appeared and rubbed his head against Harald's leg. "So you were working with them when I asked you, at home, three weeks ago?"

"No, not then. I was left out at first. Apparently they thought I wasn't suitable for secret work. By Christ, they were right. But now they're desperate, so I'm in it. I have to take pictures of some machinery at the military base on Sande."

Harald nodded. "I drew a sketch of it for Poul."

"Even you were in it before me," Arne said bitterly. "Well, well."

"Poul told me not to tell you."

"Apparently everyone thought I was a coward."

"I could redraw my sketches . . . although they were only from memory."

Arne shook his head. "They need accurate photos. I came to ask you if there's a way to sneak inside."

Harald found this talk of espionage exciting, but it bothered him that Arne did not seem to have a well-thought-out plan. "There's a place where the fence is concealed by trees, yes - but how are you going to get to Sande if the police are looking for you?"

"I've changed my appearance."

"Not much. What papers are you carrying?"

"Only my own - how would I get any others?"

"So if you're stopped by the police for any reason, it will take them about ten seconds to establish that you're the man they're all looking for."

"That's about it."

Harald shook his head. "It's crazy."

"It has to be done. This equipment enables the Germans to detect bombers when they're still miles away - in time to scramble their fighters."

"It must use radio waves," Harald said excitedly.

"The British have a similar system, but the Germans seem to have refined it, and they're shooting down up to half the aircraft on a raid. The RAF is desperate to figure out how they're doing it. It's worth risking my life."

"Not pointlessly. If you're caught, you won't be able to pass the information to the British."

"I have to try."

Harald took a deep breath. "Why don't I go?"

"I knew you were going to say that."

"No one's looking for me. I know the site. I've already been over the fence - I took a shortcut one night. And I know more about radio than you, so I'll have a better idea of what to photograph." Harald thought the logic of his argument irresistible.

"If you're caught, you'll be shot as a spy."

"Same applies to you - only you're virtually certain to be caught, whereas I'll probably get away with it."

"The police may have found your sketches when they came for Poul. If so, the Germans must know that someone's interested in the base on Sande, and they will probably have improved their security as a result. Getting over the fence may not be as easy as it was."

"I still have a better chance than you."

"I can't send you into danger. What if you're caught - what will I say to Mother?"

"You'll say that I died fighting for freedom. I've as much right as you to take the risk. Give me the damn camera."

Before Arne could reply, Karen came in.

She walked softly and appeared without warning, so Arne had no chance to hide, although reflexively he made a move to get up, then stopped himself.

"Who are you?" Karen said with her customary directness. "Oh! Hello, Arne. You've shaved off your moustache - I suppose that's because of all the posters I saw in Copenhagen today. Why are you an outlaw?" She sat on the covered hood of the Rolls-Royce, crossing her long legs like a fashion model.

Arne hesitated, then said, "I can't tell you."

Karen's agile mind raced ahead, drawing inferences with impressive speed. "My God, you're in the Resistance! Was Poul in it, too? Is that why he died?"

Arne nodded. "He didn't crash his aircraft. He was trying to escape from the police, and they shot at him."

"Poor Poul." She looked away for a moment. "So you've taken up where he left off. But now the police are on to you. Someone must be sheltering you - probably Jens Toksvig, he was Poul's closest friend after you."

Arne shrugged and nodded.

"But you can't move around without risking arrest, so . . ." She looked at Harald, and her voice went quiet. "You're in it now, Harald."

To Harald's surprise, she looked concerned, as if she were afraid for him. He was pleased that she cared.

He looked at Arne. "Well? Am I in it?"

Arne sighed and gave him the camera.

Harald arrived in Morlunde late the following day. He left the steam bike in a car park next to the ferry dock, feeling it would be too conspicuous on Sande. He had nothing with which to cover it, and no way of locking it, but he trusted that a casual thief would be unable to figure out how to make it go.

He was in time for the last ferry of the day. As he waited on the dockside, the evening slowly dimmed, and stars appeared like the lights of distant ships on a dark sea. A drunk islander came staggering along the quay, peered rudely at Harald, muttered, "Ah, young Olufsen," then sat on a capstan some distance away and tried to light a pipe.

The boat docked and a handful of people got off. To Harald's surprise, a Danish policeman and a German soldier stood at the head of the gangway. As the drunk boarded, they checked his identity card. Harald's heartbeat seemed to falter. He hesitated, scared, unsure whether to board. Had they simply stepped up security after finding his sketches, as Arne had forecast? Or were they looking for Arne himself? Would they know Harald was the brother of the wanted man? Olufsen was a common name - but they might have been briefed on the family. He had an expensive camera in his satchel. It was a popular German make, but all the same it could arouse suspicion.

He tried to calm his mind and consider his options. There were other ways of getting to Sande. He was not sure he could swim two miles in the open sea, but he might be able to borrow or steal a small boat. However, if he were seen beaching the boat on Sande he would be sure to be questioned. He might do better to act innocent.

He boarded the ferry.

The policeman asked him, "What is your reason for wanting to travel to Sande?"

Harald suppressed a feeling of indignation that anyone should presume to ask such a question. "I live there," he said. "With my parents."

The policeman looked at his face. "I don't remember seeing you before, and I've been doing this for four days."

"I've been away at school."

"Tuesday is a strange day to come home."

"It's the end of term."

The policeman grunted, apparently satisfied. He checked the address on Harald's card and showed it to the soldier, who nodded and let Harald on board.

He went to the far end of the boat and stood looking out to sea, waiting for his heart to stop racing. He was relieved to have passed the checkpoint, but furious that he had to justify himself to a policeman when moving around his own country. It seemed a silly reaction, when he thought about it logically, but he could not help feeling outraged.

At midnight the boat left the dock.

There was no moon. In the starlight, the flat island of Sande was a dark swell like another wave on the horizon. Harald had not expected to return so soon. In fact, when he left on Friday he had wondered if he would ever see the place again. Now he was back as a spy, with a camera in his bag and a mission to photograph the Nazis' secret weapon. He vaguely recalled thinking what a thrill it would be to become part of the Resistance. In reality, it was no fun at all. On the contrary, he was sick with fear.

He felt worse as he disembarked on the familiar quay and looked across the road to the post office and the grocery store that had not changed since he could remember. His life had been secure and stable for the first eighteen years. Now he would never feel safe again.

He made his way to the beach and began to tramp south. The wet sand gleamed silver in the starlight. He heard a girlish giggle from an unseen source in the dunes, and he felt a pang of jealousy. Would he ever make Karen giggle like that?

It was near dawn when he came within sight of the base. He could make out the fence posts. The trees and bushes inside the site showed as dark patches on the dunes. If he could see, so could the guards, he realized. He dropped to his knees and began to crawl forward.

A minute later he was glad of his caution. He spotted two guards patrolling inside the fence, side by side, with a dog.

That was new. They had not patrolled in pairs before, and there had been no dogs.

He dropped flat. The two men did not seem especially alert. They were strolling, not marching. The one holding the dog was talking animatedly while the other smoked. As they came nearer, Harald could hear the voice over the sound of the waves breaking on the beach. He had learned German in school, like all Danish children. The man was telling a boastful story about a woman called Margareta.

Harald was about fifty yards from the fence. As the guards approached the nearest point to him, the dog sniffed the air. It could probably smell Harald, but did not know where he was. It barked uncertainly. The guard holding the lead was not as well trained as the dog, and he told the animal to shut up, then carried on explaining how he got Margareta to meet him in the woodshed. Harald lay completely still. The dog barked again, and one of the guards turned on a powerful flashlight. Harald hid his face in the sand. The beam of the flashlight played along the dunes but passed over him without stopping.

The guard said, "Then she said all right, but you'll have to pull it out at the last minute." They walked on, and the dog became quiet again.

Harald lay still until they were out of sight. Then he turned inland and approached the section of the fence that was concealed by vegetation. He feared the soldiers might have cut down the trees, but the copse was still there. He crawled through the bushes, reached the fence, and stood up.

He hesitated. He could back out at this point, and he would have broken no law. He could return to Kirstenslot and concentrate on his new job, spending his evenings in the tavern and his nights dreaming of Karen. He could take the attitude that war and politics were none of his concern, as many Danes did. But even as he contemplated that line, he was revolted. He imagined himself explaining his decision to Arne and Karen, or Uncle Joachim and cousin Monika, and he felt ashamed just for thinking about it.

The fence was unchanged, six feet of chicken wire topped by two strands of barbed wire. Harald swung his satchel around to his back, to keep it out of the way, then climbed the fence, stepped gingerly over the barbed wire, and jumped down the other side.

Now he was committed. He was inside a military base with a camera. If they caught him, they would kill him.

He walked quickly forward, treading softly, keeping close to bushes and trees, looking around constantly. He passed the searchlight tower, and thought with trepidation how utterly exposed he would be if someone decided to switch on the powerful beams. He listened hard for patrolling footsteps, but heard only the constant hushing urged by the waves. After a few minutes he descended a gentle slope and entered a stand of conifers which provided him with good cover. He wondered for a moment why the soldiers had not thought of chopping down the trees, for better security; then he realized that they served to conceal the secret radio equipment from prying eyes.

A moment later he reached his destination. Now that he knew what he was looking for, he could see quite clearly the circular wall and the big rectangular grid rising from its hollow core, the aerial slowly rotating, like a mechanical eye scanning the dark horizon. He heard again the low hum of the electric motor. On either side of the structure he could make out the two smaller shapes, and now in the starlight he saw that they were miniature versions of the big rotating aerial.

So there were three machines. He wondered why. Might that somehow explain the remarkable superiority of German radar? Looking more closely at the smaller aerials, he thought they were constructed differently. He would need to look again in daylight, but it seemed to him they might tilt as well as rotate. Why would that be? He must make sure to get good photographs of all three pieces of apparatus.

The first time he was here, he had jumped over the circular wall in a fright, after hearing a guard cough nearby. Now that he had time to think, he felt sure there must be an easier way in. The walls were needed to protect the equipment from accidental damage, but engineers surely needed to get inside for maintenance. He walked around the circle, peering at the brickwork in the dim light, and came across a wooden door. It was not locked, and he passed through, quietly closing it behind him.

He felt a little safer. No one could see him from outside. Engineers would not do maintenance at this time of night except in an emergency. If someone did come in, he might just have time to leap over the wall before he was spotted.

He looked up at the great revolving grid. It must pick up radio beams reflected off aircraft, he guessed. The aerial must act like a lens, focusing the signals received. The cable protruding from the base carried the data back to the new buildings Harald had helped to construct last summer. There, presumably, monitors displayed the results, and operators stood ready to alert the Luftwaffe.

In the half-dark, with the humming machinery looming over him and the ozone smell of electricity in his nostrils, he felt he was inside the beating heart of the war machine. The struggle between the scientists and engineers on both sides could be as important as the battlefield clash of tanks and machine guns. And he had become part of it.

He heard an aircraft. There was no moon, so it was not likely to be a bomber. It might be a German fighter on a local flight, or a civilian transport that had got lost. He wondered if the big aerial had detected its approach an hour ago. He wondered whether the smaller aerials were pointed at it. He decided to step outside and take a look.

One of the smaller aerials faced the sea, in the direction from which the aircraft was approaching. The other pointed inland. Both were tilted at angles different from previously, he thought. As the aircraft roared closer, he noticed the first aerial tilt more, as if following it. The other continued to move, though in response to what he could not figure.

The aircraft crossed Sande and headed inland, the aerial dish continuing to follow it until after its sound died away to nothing. Harald returned to his hiding place inside the circular wall, musing on what he had seen.

The sky was turning from black to gray. At this time of year, dawn broke before three o'clock. In another hour, the sun would rise.

He took the camera out of his satchel. Arne had shown him how to use it. As daylight strengthened, he moved quietly around inside the wall, figuring out the best angles for photographs that would reveal every detail of the machinery.

He and Arne had agreed he would take the shots at about a quarter to five. The sun would be up, but it would not be shining over the wall into the installation. Sunshine was not necessary - the film in the camera was sensitive enough to record details without it.

As time went by, Harald's thoughts turned anxiously to escape. He had arrived at night, and entered the base cloaked by darkness, but he could not wait until tomorrow night before leaving. It was almost certain that an engineer would routinely inspect the equipment at least once during the course of a day, even if nothing went wrong. So Harald had to get away as soon as he had taken the photos - when it would be full daylight. His departure would be a lot more dangerous than his arrival.

He considered which way to go. To the south of where he was, in the direction of his parents' home, the fence was only a couple of hundred yards away, but the route lay across open dunes without trees or bushes. Going north, retracing his steps, under cover of vegetation much of the way, would take longer but might be safer.

He wondered how he would face a firing squad. Would he be calm and proud, keeping his terror under control, or would he break and turn into a gibbering fool, pleading for mercy and wetting himself?

He forced himself to wait calmly. The light grew stronger and the minute hand crawled around the face of his watch. He heard no new sounds from outside. A soldier's day started early, but he was hoping there would not be much activity before six o'clock - by which time he would be gone.

At last it was time to take the pictures. The sky was cloudless and there was a clear morning light. He could see every rivet and terminal of the complex piece of machinery in front of him. Focusing the lens carefully, he photographed the revolving base of the apparatus, the cables, and the grid of the aerial. He unfolded a yard rule from the monastery tool rack and placed it in some of the pictures to show scale - his own bright idea.

Next he had to go outside the wall.

He hesitated. In here he felt safe. But he had to have pictures of the two smaller aerials.

He cracked the door. All was still. He could tell, by the sound of the surf, that the tide was coming in. The base was bathed in the watery light of a seaside morning. There was no sign of life. It was the hour when men sleep heavily, and even dogs have dreams.

He took careful shots of the two smaller aerials, which were protected only by low walls. Thinking about their function, he realized that one of them had been tracking an aircraft that was within visual range. The whole point of this apparatus was to detect bombers before they came into sight, he had thought. Presumably the second small aerial was tracking another aircraft.

Snapping photographs, he turned the puzzle over in his mind. How could three devices work together to increase the kill rate of Luftwaffe fighters? Perhaps the large aerial gave advance warning of a bomber's approach and the smaller one tracked the bomber within German airspace. But then what did the second smaller aerial do?

It occurred to him that there would be another aircraft in the sky - the fighter that had been scrambled to attack the bomber. Could the second aerial be used by the Luftwaffe to track their own aircraft? It seemed crazy, but as he stepped back to photograph the three aerials together, showing their placement relative to one another, he realized it made perfect sense. If a Luftwaffe controller knew the positions of the bomber and the fighter, he could direct the fighter by radio until it made contact with the bomber.

He began to see how the Luftwaffe might be working. The large aerial gave advance warning of a raid so that the fighters could be scrambled in time. One of the smaller aerials picked up a bomber as it came closer. The other tracked a fighter, enabling the controller to direct the pilot precisely to the bomber's location. After that, it was like shooting fish in a barrel.

That thought made Harald realize how exposed he was: standing upright, in full daylight, in the middle of a military base, photographing top secret equipment. Panic surged through his veins like poison. He tried to calm himself and take the last few photos he had planned, showing the three aerials from different angles, but he was too terrified. He had taken at least twenty shots. It must be enough, he told himself.

He thrust the camera into his satchel and started walking quickly away. Forgetting his resolution to take the longer but safer route north, he headed south, across the open dunes. In that direction the fence was visible, just beyond the old boathouse he had bumped into last time. Today he would pass it on the seaward side, and it would hide him from sight for a few paces.

As he approached it, a dog barked.

He looked around wildly but saw no soldiers and no dog. Then he realized the sound had come from the boathouse. The soldiers must be using the derelict building as a kennel. A second dog joined the barking.

Harald broke into a run.

The dogs excited one another, more joined in, and the noise became hysterically loud. Harald reached the building then turned seaward, trying to keep the boathouse between himself and the main buildings while he sprinted for the fence. Fear gave him speed. Every second he expected a shot to ring out.

He reached the fence, not knowing whether he had been seen or not. He climbed it like a monkey and vaulted over the barbed wire at the top. He came down hard on the other side, splashing in shallow water. He scrambled to his feet and glanced back through the fence. Beyond the boathouse, partly obscured by trees and bushes, he could see the main buildings, but no soldiers were in view. He turned away and ran. He stayed in the shallow water for a hundred yards, so that the dogs could not follow his scent, then he turned inland. He left shallow footprints in the hard sand, but he knew the fast-moving tide would cover them in a minute or two. He reached the dunes, where he left no visible trace.

A few minutes later he came to the dirt road. He glanced back and saw no one following. Breathing hard, he headed for the parsonage. He ran past the church to the kitchen door.

It was open. His parents were always up early.

He stepped inside. His mother was at the stove, wearing a dressing gown, making tea. When she saw him she gave a cry of shock and dropped the earthenware teapot. It hit the tiled floor and the spout broke off. Harald picked up the two pieces. "I'm sorry to startle you," he said.

"Harald!"

He kissed her cheek and hugged her. "Is my father at home?"

"In the church. There wasn't time to tidy up last night, so he's gone to straighten the chairs."

"What happened last night?" There was no service on a Monday evening.

"The board of deacons met to discuss your case. They're going to read you out next Sunday."

"The revenge of the Flemmings." Harald found it strange that he had once thought that sort of thing important.

By now, guards would have gone to find out what had disturbed the dogs. If they were thorough, they might check nearby houses, and look for a fugitive in sheds and barns. "Mother," he said, "if the soldiers come here, will you tell them I've been in bed all night?"

"Whatever has happened?" she said fearfully.

"I'll explain later." It would be more natural if he were in bed, he thought. "Tell them I'm still asleep - will you?"

"All right."

He left the kitchen and went upstairs to his bedroom. He slung his satchel over the back of the chair. He took the camera out and put it in a drawer. He thought of hiding it, but there was no time, and a hidden camera was proof of guilt. He shed his clothes quickly, put on his pajamas, and got into bed.

He heard his father's voice in the kitchen. He got out of bed and went to the top of the stairs to listen.

"What's he doing here?" the pastor said.

His mother replied, "Hiding from the soldiers."

"For goodness' sake, what has the boy got himself into now?"

"I don't know, but - "

His mother was interrupted by a loud knocking. A young man's voice said in German, "Good morning. We're looking for someone. Have you seen a stranger at any time in the last few hours?"

"No, nobody at all." The nervousness in his mother's voice was so evident that the soldier must have noticed it - but perhaps he was used to people being frightened of him.

"How about you, sir?"

His father said firmly, "No."

"Is there anyone else here?"

Harald's mother replied, "My son. He's still asleep."

"I need to search the house." The voice was polite, but it was making a statement, not asking permission.

"I'll show you around," said the pastor.

Harald returned to his bed, heart thudding. He heard booted footsteps on the tiled floors downstairs, and doors opening and closing. Then the boots came up the wooden staircase. They entered his parents' bedroom, then Arne's old room, and finally approached Harald's. He heard the handle of his door turn.

He closed his eyes, feigning sleep, and tried to make his breathing slow and even.

The German voice said quietly, "Your son."

"Yes."

There was a pause.

"Has he been here all night?"

Harald held his breath. He had never known his father to tell even a white lie.

Then he heard, "Yes. All night."

He was flabbergasted. His father had lied for him. The hard-hearted, stiff-necked, self-righteous old tyrant had broken his own rules. He was human after all. Harald felt tears behind his closed eyelids.

The boots receded along the passage and down the stairs, and Harald heard the soldier take his leave. He got out of bed and went to the top of the stairs.

"You can come down now," his father said. "He's gone."

He went down. His father looked solemn. "Thank you for that, Father," Harald said.

"I committed a sin," his father said. For a moment, Harald thought he was going to be angry. Then the old face softened. "However, I believe in a forgiving God."

Harald realized the agony of conflict his father had been through in the last few minutes, but he did not know how to say that he understood. The only thing he could think of was to shake hands. He held out his hand.

His father looked at it, then took it. He drew Harald to him and put his left arm around Harald's shoulders. He closed his eyes, struggling to contain a profound emotion. When he spoke, the resonant boom of the preacher had gone from his voice, and his words came out in a murmur of anguish. "I thought they would kill you," he said. "My dear son, I thought they would kill you."