“One thing I don’t get,” Leo said. “Why Commodus? I mean, if this Triumvirate is the three biggest and baddest emperors, the Roman supervillain dream team…Nero makes sense. But Commode Man? Why not some eviler, more famous guy, like Murderous Maximus or Attila the Hun?”

“Attila the Hun was not a Roman emperor,” I said. “As for Murderous Maximus…well, that’s actually a good name, but not a real emperor. As for why Commodus is part of the Triumvirate—”

“They think he’s weak,” Meg said.

She kept her gaze on our wake, as if she saw her own assortment of faces below the surface.

“You know this how?” I asked.

“My step—Nero told me. Him and the third one, the emperor in the west, they wanted Commodus between them.”

“The third emperor,” I said. “You know who he is?”

Meg frowned. “I only saw him once. Nero never used his name. He just called him my kinsman. I think even Nero is afraid of him.”

“Fantastic,” I muttered. Any emperor who scared Nero was not someone I wanted to meet.

“So Nero and the dude in the west,” Leo said, “they want Commodus to be a buffer between them. Monkey in the middle.”

Meg rubbed her nose. “Yeah. Nero told me….He said Commodus was like his Peaches. A vicious pet. But controllable.”

Her voice wavered on the name of her karpos companion.

I was afraid Meg might order me to slap myself or jump in the canal, but I asked, “Where is Peaches?”

She stuck out her lower lip. “The Beast—”

“Nero,” I corrected gently.

“Nero took him. He said—he said I didn’t deserve a pet until I behaved.”

Anger made me pedal faster, made me almost welcome the chafing pain on my ankle. I didn’t know how Nero had managed to imprison the grain spirit, but I understood why he’d done it. Nero wanted Meg to depend entirely on him. She wasn’t allowed to have her own possessions, her own friends. Everything in her life had to be tainted with Nero’s poison.

If he got his hands on me, no doubt he would use me the same way. Whatever horrible tortures he had planned for Lester Papadopoulos, they wouldn’t be as bad as the way he tortured Meg. He would make her feel responsible for my pain and death.

“We’ll get Peaches back,” I promised her.

“Yeah, chica,” Leo agreed. “The Dread Pirate Valdez never abandons a crew member. Don’t you worry about—”

“Guys.” Meg’s voice took on a sharp edge. “What’s that?”

She pointed to starboard. A line of chevrons rippled on the green water—like an arrow had been shot horizontally across the surface.

“Did you see what it was?” Leo asked.

Meg nodded. “A—a fin, maybe? Do canals have fish?”

I didn’t know the answer, but I didn’t like the size of those ripples. My throat felt as if it were sprouting fresh wheat shoots.

Leo pointed off the bow. “There.”

Right in front of us, about half an inch below the surface, green scales undulated, then submerged.

“That’s not a fish,” I said, hating myself for being so perceptive. “I think that’s another part of the same creature.”

“As over there?” Meg pointed again to starboard. The two disturbances had happened at least forty feet apart. “That would mean something bigger than the boat.”

Leo scanned the water. “Apollo, any idea what that thing is?”

“Only a hunch,” I said. “Let’s hope I’m wrong. Pedal faster. We have to find that grate.”

Get me a legion

And about six tons of rocks

Need to kill a snake

I DO NOT LIKE SERPENTS.

Ever since my famous battle with Python, I’ve had a phobia of scaly reptilian creatures. (Especially if you include my stepmother, Hera. BOOM!) I could barely tolerate the snakes on Hermes’s caduceus, George and Martha. They were friendly enough, but they constantly pestered me to write a song for them about the joy of eating rats—a joy I did not share.

I told myself the creature in the Central Canal wasn’t an aquatic serpent. The water was much too cold. The canal didn’t offer enough tasty fish to eat.

On the other hand, I knew Commodus. He loved to collect exotic monsters. I could think of one particular river serpent he would love—one that might easily sustain itself by eating tasty pedal-boaters….

Bad Apollo! I told myself. Stay focused on your mission!

We chugged along for another fifty feet or so, long enough for me to wonder if the threat had been imaginary. Perhaps the monster had been nothing more than an abandoned pet alligator. Did they have those in the Midwest? Very polite ones, perhaps?

Leo nudged me. “Look over there.”

On the far embankment wall, peeking above the waterline, was the brick archway of an old sewer main, the entrance blocked by golden bars.

“How many sewers have you seen with gold grates on them?” Leo asked. “Betcha that one leads right to the emperor’s palace.”

I frowned. “That was much too easy.”

“Hey.” Meg poked me in the back of the neck. “Remember what Percy told us? Never say stuff like We made it or That was easy. You’ll jinx us!”

“My entire existence is a jinx.”

“Pedal faster.”

Since that was a direct order from Meg, I had no choice. My legs already felt like they were turning into sacks of hot coals, but I picked up the pace. Leo steered our teal plastic pirate ship toward the sewer entrance.

We were ten feet away when we triggered the First Law of Percy Jackson. Our jinx rose from the water in the form of a glistening arc of serpentine flesh.

I may have screamed. Leo shouted a completely unhelpful warning: “Look out!”

The boat tilted sideways. More arcs of serpent flesh breached around us—undulating hills of green and brown ridged with serrated dorsal fins. Meg’s twin blades flashed into existence. She tried to stand, but the pedal boat capsized, plunging us into a cold green explosion of bubbles and thrashing limbs.

My only consolation: the canal was not deep. My feet found the bottom and I was able to stand, gasping and shivering, the water up to my shoulders. Nearby, a three-foot-diameter coil of serpent flesh encircled our pedal boat and squeezed. The hull imploded, shattering teal plastic with a sound like firecrackers. One shard stung my face, narrowly missing my left eye.

Leo popped to the surface, his chin barely at water level. He waded toward the sewer grate, climbing over a hill of serpent flesh that got in his way. Meg, bless her heroic heart, slashed away at the monster’s coils, but her blades just skidded off its slimy hide.

Then the creature’s head rose from the canal, and I lost all hope that we would be home in time for tofu enchilada night.

The monster’s triangular forehead was wide enough to provide parking for a compact car. Its eyes glowed as orange as Agamethus’s ghost. When it opened its vast red maw, I remembered another reason I hate serpents. Their breath smells worse than Hephaestus’s work shirts.

The creature snapped at Meg. Despite being neck-deep in water, she somehow sidestepped and thrust her left-handed blade straight into the serpent’s eye.