“Hold on, Nico,” I said. “It’s high time you explained who these cave-runners are.”

The son of Hades fixed his dark eyes on me as if I were another layer of concrete to dig through. “A few months ago, I made contact with the troglodytes.”

I choked on a laugh. Nico’s claim was the most ridiculous thing I’d heard since Mars swore to me that Elvis Presley was alive on, well, Mars.

“Troglodytes are a myth,” I said.

Nico frowned. “A god is telling a demigod that something is a myth?”

“Oh, you know what I mean! They aren’t real. That trashy author Aelian made them up to sell more copies of his books back in ancient Rome. A race of subterranean humanoids who eat lizards and fight bulls? Please. I’ve never seen them. Not once in my millennia of life.”

“Did it ever occur to you,” Nico said, “that troglodytes might go out of their way to hide from a sun god? They hate the light.”

“Well, I—”

“Did you ever actually look for them?” Nico persisted.

“Well, no, but—”

“They’re real,” Will confirmed. “Unfortunately, Nico found them.”

I tried to process this information. I’d never taken Aelian’s stories about the troglodytes seriously. To be fair, though, I hadn’t believed in rocs, either, until the day one flew over my sun chariot and bowel-bombed me. That was a bad day for me, the roc, and several countries that my swerving chariot set on fire.

“If you say so. But do you know how to find the troglodytes again?” I asked. “Do you think they would help us?”

“Those are two different questions,” Nico said. “But I think I can convince them to help. Maybe. If they like the gift I got them. And if they don’t kill us on sight.”

“I love this plan,” Will grumbled.

“Guys,” Rachel said, “you forgot about me.”

I stared at her. “What do you mean?”

“I’m coming, too.”

“Certainly not!” I protested. “You’re mortal!”

“And essential,” Rachel said. “Your prophecy told you so. A Dare reveals the path that was unknown. All I’ve done so far is show you blueprints, but I can do more. I can see things you can’t. Besides, I’ve got a personal stake in this. If you don’t survive the Tower of Nero, you can’t fight Python. And if you can’t defeat him…”

Her voice faltered. She swallowed and doubled over, choking.

At first, I thought some of her Yoo-hoo might have gone down the wrong way. I patted her on the back unhelpfully. Then she sat up again, her back rigid, her eyes glowing. Smoke billowed from her mouth, which is not something normally caused by chocolate drinks.

Will, Nico, and Meg scooted away in their beanbags.

I would have done the same, but for half a second I thought I understood what was happening: a prophecy! Her Delphic powers had broken through!

Then, with sickening dread, I realized this smoke was the wrong color: pallid yellow instead of dark green. And the stench…sour and decayed, like it was wafting straight from Python’s armpits.

When Rachel spoke, it was with Python’s voice—a gravely rumble, charged with malice.

“Apollo’s flesh and blood shall soon be mine.

Alone he must descend into the dark,

This sibyl never again to see his sign,

Lest grappling with me till his final spark

The god dissolves, leaving not a mark.”

The smoke dissipated. Rachel slumped against me, her body limp.

CRASH! A sound like shattering metal shook my bones. I was so terrified, I wasn’t sure if the noise was from somewhere outside, or if it was just my nervous system shutting down.

Nico got up and ran to the windows. Meg scrambled over to help me with Rachel. Will checked her pulse and started to say, “We need to get her—”

“Hey!” Nico turned from the window, his face pale with shock. “We have to get out of here now. The cows are attacking.”

IN NO CONTEXT CAN THE COWS ARE ATTACKING be considered good news.

Will picked up Rachel in a firefighter’s carry—for a gentle healer, he was deceptively strong—and together we jogged over to join Nico at the window.

In the railyard below, the cows were staging a revolution. They’d busted through the sides of their cattle cars like an avalanche through a picket fence and were now stampeding toward the Dare residence. I suspected the cattle hadn’t been trapped in those cars at all. They’d simply been waiting for the right moment to break out and kill us.

They were beautiful in a nightmarish way. Each was twice the size of a normal bovine, with bright blue eyes and shaggy red hair that rippled in dizzying whorls like a living van Gogh painting. Both cows and bulls—yes, I could tell the difference; I was a cow expert—possessed huge curved horns that would have made excellent drinking cups for the largest and thirstiest of Lu’s Celtic kinfolk.

A line of freight cars stood between us and the cows, but that didn’t deter the herd. They barreled straight through, toppling and flattening the cars like origami boxes.

“Do we fight?” Meg asked, her voice full of doubt.

The name of these creatures suddenly came back to me—too late, as usual. Earlier, I’d mentioned that troglodytes were known for fighting bulls, but I hadn’t put the facts together. Perhaps Nero had parked the cattle cars here as a trap, knowing we might seek out Rachel’s help. Or perhaps their presence was simply the Fates’ cruel way of laughing at me. Oh, you want to play the troglodyte card? We counter with cows!

“Fighting would be no use,” I said miserably. “Those are tauri silvestres—forest bulls, the Romans called them. Their hides cannot be pierced. According to legend, the tauri are ancestral enemies of Nico’s friends, the troglodytes.”

“So now you believe the trogs exist?” Nico asked.

“I am learning to believe in all sorts of things that can kill me!”

The first wave of cattle reached the Dares’ retaining wall. They plowed through it and charged the house.

“We need to run!” I said, exercising my noble duty as Lord Obvious of Duh.

Nico led the way. Will followed close behind with Rachel still draped over his shoulder, Meg and me at his back.

We were halfway down the hall when the house began to shake. Cracks zigzagged up the walls. At the top of the floating staircase, we discovered (fun fact) a floating staircase will cease to float if a forest bull tries to climb it. The lower steps had been stripped from the wall. Bulls rampaged through the corridor below like a crowd of Black Friday bargain hunters, stomping on broken steps and crashing through the atrium’s glass walls, renovating the Dares’ house with extreme prejudice.

“At least they can’t get up here,” Will said.

The floor shook again as the tauri took out another wall.

“We’ll be down there soon enough,” Meg said. “Is there another way out?”

Rachel groaned. “Me. Down.”

Will eased her to her feet. She swayed and blinked, trying to process the scene below us.

“Cows,” Rachel said.

“Yeah,” Nico agreed.