Piper’s blowgun and quiver—both heirlooms from her grandfather—were ruined. Her hair was singed. Her burned arms, glistening with aloe, looked like newly glazed brick. She called her father to warn him she would be spending the night with her study group, then settled into one of the Cistern’s brickwork alcoves with Mellie and Hedge, who kept urging her to drink more water. Baby Chuck sat in Piper’s lap, staring enraptured at her face as if it were the most amazing thing in the world.

As for Meg, she sat glumly by the pool, her feet in the water, a plate of cheese enchiladas in her lap. She wore a baby blue T-shirt from Macro’s Military Madness featuring a smiling cartoon AK-47 with the caption: SHOOTIE’S JUNIOR MARKSMAN CLUB! Next to her sat Agave, looking dejected, though a new green spike had started to grow where her withered arm had fallen off. Her dryad friends kept coming by, offering her fertilizer and water and enchiladas, but Agave shook her head glumly, staring at the collection of fallen money maker petals in her hand.

Money Maker, I was told, had been planted on the hillside with full dryad honors. Hopefully, she would be reincarnated as a beautiful new succulent, or perhaps a white-tailed antelope squirrel. Money Maker had always loved those.

Grover looked exhausted. Playing all the healing music had taken its toll, not to mention the stress of driving back to Palm Springs at unsafe speeds in the borrowed/slightly stolen Bedrossian-mobile with five critical burn victims.

Once we had all gathered—condolences exchanged, enchiladas eaten, aloe slimed—I began the meeting.

“All of this,” I announced, “is my fault.”

You can imagine how difficult this was for me to say. The words simply had not been in the vocabulary of Apollo. I half hoped the collected dryads, satyrs, and demigods would rush to reassure me that I was blameless. They did not.

I forged on. “Caligula’s goal has always been the same: to make himself a god. He saw his ancestors immortalized after their deaths: Julius, Augustus, even disgusting old Tiberius. But Caligula didn’t want to wait for death. He was the first Roman emperor who wanted to be a living god.”

Piper looked up from playing with the baby satyr. “Caligula kind of is a minor god now, right? You said he and the two other emperors have been around for thousands of years. So he got what he wanted.”

“Partly,” I agreed. “But being a minor anything isn’t enough for Caligula. He always dreamed of replacing one of the Olympians. He toyed with the idea of becoming the new Jupiter or Mars. In the end, he set his sights on being”—I swallowed the sour taste from my mouth—“the new me.”

Coach Hedge scratched his goatee. (Hmm. If a goat wears a goatee, is it a man-tee?) “So, what? Caligula kills you, puts on a Hi, I’m Apollo! name tag, and walks into Olympus hoping nobody notices?”

“It would be worse than killing me,” I said. “He would consume my essence, along with the essence of Helios, to make himself the new sun god.”

Prickly Pear bristled. “The other Olympians would just allow this?”

“The Olympians,” I said bitterly, “allowed Zeus to strip me of my powers and toss me to earth. They’ve done half of Caligula’s job for him. They won’t interfere. As usual, they’ll expect heroes to set things right. If Caligula does become the new sun god, I will be gone. Permanently gone. That’s what Medea has been preparing for with the Burning Maze. It’s a giant cooking pot for sun-god soup.”

Meg wrinkled her nose. “Gross.”

For once, I was in total agreement with her.

Standing in the shadows, Joshua Tree crossed his arms. “So the fires of Helios—that’s what’s killing our land?”

I spread my hands. “Well, humans aren’t helping. But on top of the usual pollution and climate change, yes, the Burning Maze was the tipping point. Everything that’s left of the Titan Helios is now coursing through this section of the Labyrinth under Southern California, slowly turning the top side into a fiery wasteland.”

Agave touched the side of her scarred face. When she looked up at me, her stare was as pointed as her collar. “If Medea succeeds, will all the power go into Caligula? Will the maze stop burning and killing us?”

I had never considered cacti a particularly vicious life-form, but as the other dryads studied me, I could imagine them tying me up with a ribbon and a large card that said FOR CALIGULA, FROM NATURE and dropping me on the emperor’s doorstep.

“Guys, that won’t help,” Grover said. “Caligula’s responsible for what’s happening to us right now. He doesn’t care about nature spirits. You really want to give him the full power of a sun god?”

The dryads muttered in reluctant agreement. I made a mental note to send Grover a nice card on Goat Appreciation Day.

“So what do we do?” asked Mellie. “I don’t want my son growing up in a burning wasteland.”

Meg took off her glasses. “We kill Caligula.”

It was jarring, hearing a twelve-year-old girl speak so matter-of-factly about assassination. Even more jarring, I was tempted to agree with her.

“Meg,” I said, “that may not be possible. You remember Commodus. He was the weakest of the three emperors, and the best we could do was force him out of Indianapolis. Caligula will be much more powerful, more deeply entrenched.”

“Don’t care,” she muttered. “He hurt my dad. He did…all this.” She gestured around at the old cistern.

“What do you mean all this?” Joshua asked.

Meg shot a look at me as if to say Your turn.

Once again, I explained what I had seen in Meg’s memories—Aeithales as it had once been, the legal and financial pressure Caligula must have used to shut down Phillip McCaffrey’s work, the way Meg and her father had been forced to flee just before the house was firebombed.

Joshua frowned. “I remember a saguaro named Hercules from the first greenhouse. One of the few who survived the house fire. Old, tough dryad, always in pain from his burns, but he kept clinging to life. He used to talk about a little girl who lived in the house. He said he was waiting for her to return.” Joshua turned to Meg in amazement. “That was you?”

Meg brushed a tear from her cheek. “He didn’t make it?”

Josh shook his head. “He died a few years ago. I’m sorry.”

Agave took Meg’s hand. “Your father was a great hero,” she said. “Clearly, he was doing his best to help plants.”

“He was a…botanist,” Meg said, pronouncing the word as if she’d just remembered it.

The dryads lowered their heads. Hedge and Grover removed their hats.

“I wonder what your dad’s big project was,” Piper said, “with those glowing seeds. What did Medea call you…a descendant of Plemnaeus?”

The dryads let out a collective gasp.

“Plemnaeus?” asked Reba. “The Plemnaeus? Even in Argentina, we know of him!”

I stared at her. “You do?”

Prickly Pear snorted. “Oh, come on, Apollo! You’re a god. Surely you know of the great hero Plemnaeus!”

“Um…” I was tempted to blame my faulty mortal memory, but I was pretty sure I had never heard the name, even when I was a god. “What monster did he slay?”