‘They love shiny metal,’ Beckendorf whispered. ‘Especially gold. I’ve heard they have more gold in their nest than Fort Knox.’ He sounded envious.

‘Don’t even think about it,’ I said.

‘Dude, I won’t,’ he promised. ‘Let’s get out of here while we…’

His eyes widened.

Fifteen metres away, two ants were struggling to drag a big hunk of metal towards their nest. It was the size of a refrigerator, all glittery gold and bronze, with weird bumps and ridges down the side and a bunch of wires sticking out the bottom. Then the ants rolled the thing over, and I saw a face.

I just about jumped out of my skin. ‘That’s a –’

‘Shhh!’ Beckendorf pulled me back into the bushes.

‘But that’s a –’

‘Dragon’s head,’ he said in awe. ‘Yes. I see it.’

The snout was as long as my body. The mouth hung open, showing metal teeth like a shark’s. Its skin was a combination of gold and bronze scales, and its eyes were rubies as big as my fists. The head looked like it had been hacked from its body – chewed by ant mandibles. The wires were frayed and tangled.

The head must’ve been heavy, too, because the ants were struggling, moving it only a few centimetres with every tug.

‘If they get it to the hill,’ Beckendorf said, ‘the other ants will help them. We’ve got to stop them.’

‘What?’ I asked. ‘Why?’

‘It’s a sign from Hephaestus. Come on!’

I didn’t know what he was talking about, but I’d never seen Beckendorf look so determined. He sprinted along the edge of the clearing, his armour blending into the trees.

I was about to follow when something sharp and cold pressed against my neck.

‘Surprise,’ Annabeth said, right next me. She must’ve had her magic Yankees cap on because she was totally invisible.

I tried to move, but she dug her knife under my chin. Silena appeared out of the woods, her sword drawn. Her Aphrodite armour was pink and red, colour coordinated to match her clothes and makeup. She looked like Guerilla Warfare Barbie.

‘Nice work,’ she told Annabeth.

An invisible hand confiscated my sword. Annabeth took off her cap and appeared before me, smiling smugly. ‘Boys are easy to follow. They make more noise than a lovesick Minotaur.’

My face felt hot. I tried to think back, hoping I hadn’t said anything embarrassing. No telling how long Annabeth and Silena had been eavesdropping.

‘You’re our prisoner,’ Annabeth announced. ‘Let’s get Beckendorf and –’

‘Beckendorf!’ For a split second I’d forgotten about him, but he was still forging ahead – straight towards the dragon’s head. He was already twelve metres away. He hadn’t noticed the girls, or the fact that I wasn’t behind him.

‘Come on!’ I told Annabeth.

She pulled me back. ‘Where do you think you’re going, prisoner?’

‘Look!’

She peered into the clearing and for the first time seemed to realize where we were. ‘Oh, Zeus…’

Beckendorf leaped into the open and struck one of the ants. His sword clanged off the thing’s carapace. The ant turned, snapping its pincers. Before I could even call out, the ant bit Beckendorf’s leg, and he crumpled to the ground. The second ant sprayed goo in his face, and Beckendorf screamed. He dropped his sword and slapped wildly at his eyes.

I surged forward, but Annabeth pulled me back. ‘No.’

‘Charlie!’ Silena yelled.

‘Don’t!’ Annabeth hissed. ‘It’s already too late!’

‘What are you talking about?’ I demanded. ‘We have to –’

Then I noticed more ants swarming towards Beckendorf – ten, twenty. They grabbed him by the armour and dragged him towards the hill so fast he was swept into a tunnel and disappeared.

‘No!’ Silena pushed Annabeth. ‘You let them take Charlie!’

‘There’s no time to argue,’ Annabeth said. ‘Come on!’

I thought she was going to lead us on a charge to save Beckendorf, but instead she raced to the dragon’s head, which the ants had momentarily forgotten. She grabbed it by the wires and started dragging it towards the woods.

‘What are you doing?’ I demanded. ‘Beckendorf –’

‘Help me,’ Annabeth grunted. ‘Quick, before they get back.’

‘Oh, my gods!’ Silena said. ‘You’re more worried about this hunk of metal than Charlie?’

Annabeth spun around and shook her by the shoulders. ‘Listen, Silena! Those are Myrmekes. They’re like fire ants, only a hundred times worse. Their bite is poison. They spray acid. They communicate with all the other ants and swarm over anything that threatens them. If we’d rushed in there to help Beckendorf, we would have been dragged inside, too. We’re going to need help – a lot of help – to get him back. Now, grab some wires and pull!’

I didn’t know what Annabeth was up to, but I’d adventured with her long enough to figure she had a good reason for what she was doing. The three of us tugged the metal dragon’s head into the woods. Annabeth didn’t let us stop until we were fifty metres from the clearing. Then we collapsed, sweating and breathing hard.

Silena started to cry. ‘He’s probably dead already.’

‘No,’ Annabeth said. ‘They won’t kill him right away. We’ve got about half an hour.’

‘How do you know that?’ I asked.

‘I’ve read about the Myrmekes. They paralyse their prey so they can soften them up before –’

Silena sobbed. ‘We have to save him!’

‘Silena,’ Annabeth said. ‘We’re going to save him, but I need you to get a grip. There is a way.’

‘Call the other campers,’ I said, ‘or Chiron. Chiron will know what to do.’

Annabeth shook her head. ‘They’re scattered all over the woods. By the time we got everyone back here, it would be too late. Besides, the entire camp wouldn’t be strong enough to invade the Ant Hill.’

‘Then what?’

Annabeth pointed at the dragon’s head.

‘Okay,’ I said. ‘You’re going to scare the ants with a big metal puppet?’

‘It’s an automaton,’ she said.

That didn’t make me feel any better. Automatons were magical bronze robots made by Hephaestus. Most of them were crazed killing machines, and those were the nice ones.

‘So what?’ I said. ‘It’s just a head. It’s broken.’

‘Percy, this isn’t just any automaton,’ Annabeth said. ‘It’s the bronze dragon. Haven’t you heard the stories?’

I stared at her blankly. Annabeth had been at camp a lot longer than I had. She probably knew tons of stories I didn’t.

Silena’s eyes widened. ‘You mean the old guardian? But that’s just a legend!’

‘Whoa,’ I said. ‘What old guardian?’

Annabeth took a deep breath. ‘Percy, in the days before Thalia’s tree – back before the camp had magical boundaries to keep out monsters – the counsellors tried all sorts of different ways to protect themselves. The most famous was the bronze dragon. The Hephaestus cabin made it with the blessing of their father. Supposedly it was so fierce and powerful that it kept the camp safe for over a decade. And then… about fifteen years ago, it disappeared into the woods.’

‘And you think this is its head?’

‘It has to be! The Myrmekes probably dug it up while they were looking for precious metal. They couldn’t move the whole thing, so they chewed off the head. The body can’t be far away.’

‘But they chewed it apart. It’s useless.’

‘Not necessarily.’ Annabeth’s eyes narrowed, and I could tell her brain was working overtime. ‘We could reassemble it. If we could activate it –’

‘It could help us rescue Charlie!’ Silena said.

‘Hold up,’ I said. ‘That’s a lot of ifs. If we find it, if we can reactivate it in time, if it will help us. You said this thing disappeared fifteen years ago?’

Annabeth nodded. ‘Some say its motor wore out so it went into the woods to deactivate itself. Or its programming went haywire. No one knows.’

‘You want to reassemble a haywire metal dragon?’

‘We have to try!’ Annabeth said. ‘It’s Beckendorf’s only hope! Besides, this could be a sign from Hephaestus. The dragon should want to help one of Hephaestus’s kids. Beckendorf would want us to try.’

I didn’t like the idea. On the other hand, I didn’t have any better suggestions. We were running out of time, and Silena looked like she was about to go into shock if we didn’t do something soon. Beckendorf had said something about a sign from Hephaestus. Maybe it was time to find out.

‘All right,’ I said. ‘Let’s go find a headless dragon.’

We searched forever, or maybe it just seemed that way, because the whole time, I was imagining Beckendorf in the Ant Hill, scared and paralysed, while a bunch of armoured critters scuttled around him, waiting for him to be tenderized.

It wasn’t hard to follow the ants’ trail. They’d dragged the dragon’s head through the forest, making a deep rut in the mud, and we dragged the head right back the way they’d come.

We must’ve gone five hundred metres – and I was getting worried about the time – when Annabeth said, ‘Di immortales.’

We’d come to the rim of a crater – like something had blasted a house-size hole in the forest floor. The sides were slippery and dotted with tree roots. Ant tracks led to the bottom, where a large metal mound glinted through the dirt. Wires stuck up from a bronze stump on one end.

‘The dragon’s neck,’ I said. ‘You think the ants made this crater?’

Annabeth shook her head. ‘Looks more like a meteor blast…’

‘Hephaestus,’ Silena said. ‘The god must’ve unearthed this. Hephaestus wanted us to find the dragon. He wanted Charlie to…’ She choked up.

‘Come on,’ I said. ‘Let’s reconnect this bad boy.’

Getting the dragon’s head to the bottom was easy. It tumbled right down the slope and hit the neck with a loud, metallic BONK! Reconnecting it was harder.

We had no tools and no experience.

Annabeth fiddled with the wires and cursed in Ancient Greek. ‘We need Beckendorf. He could do this in seconds.’

‘Isn’t your mom the goddess of inventors?’ I asked.

Annabeth glared at me. ‘Yes, but this is different. I’m good with ideas. Not mechanics.’

‘If I was going to pick one person in the world to reattach my head,’ I said, ‘I’d pick you.’

I just blurted it out – to give her confidence, I guess – but immediately I realized it sounded pretty stupid.

‘Awww…’ Silena sniffled and wiped her eyes. ‘Percy, that is so sweet!’