“Now, that’s interesting!” Cacus beamed.

“Uh-oh.” Annabeth took a step back.

The giant swung the staff in our direction. “Yes! Soon I will master this thing and be as powerful as Hermes. I’ll be able to go anywhere! I’ll steal anything I want, make high-quality knockoffs, and sell them around the world. I will be the lord of traveling salesmen!”

“That,” I said, “is truly evil.”

“Ha-ha!” Cacus raised the caduceus in triumph. “I had my doubts, but now I’m convinced. Stealing this staff was an excellent idea! Now let’s see how I can kill you with it.”

“Wait!” Annabeth said. “You mean it wasn’t your idea to steal the staff?”

“Kill them!” Cacus ordered the snakes. He pointed the caduceus at us, but the silver tip only spewed slips of paper. Annabeth picked up one and read it.

“You’re trying to kill us with Groupons,” she announced. “‘Eighty-five percent off piano lessons.’”

“Gah!” Cacus glared at the snakes and breathed a fiery warning shot over their heads. “Obey me!”

George and Martha squirmed in alarm.

Stop that! Martha cried.

We’re cold-blooded! George protested. Fire is not good!

“Hey, Cacus!” I shouted, trying to get back his attention. “Answer our question. Who told you to steal the staff?”

The giant sneered. “Foolish demigod. When you defeated Kronos, did you think you eliminated all the enemies of the gods? You only delayed the fall of Olympus for a little while longer. Without the staff, Hermes will be unable to carry messages. Olympian communication lines will be disrupted, and that’s only the first bit of chaos my friends have planned.”

“Your friends?” Annabeth asked.

Cacus waved off the question. “Doesn’t matter. You won’t live that long, and I’m only in it for the money. With this staff, I’ll make millions! Maybe even thousands! Now hold still. Perhaps I can get a good price on two demigod statues.”

I wasn’t fond of threats like that. I’d had enough of them a few years ago when I fought Medusa. I wasn’t anxious to fight this guy, but I also knew I couldn’t leave George and Martha at his mercy. Besides, the world had enough traveling salesmen. Nobody deserved to answer their door and find a fire-breathing giant with a magic staff and a collection of knockoff Rolexes.

I looked at Annabeth. “Time to fight?”

She gave me a sweet smile. “Smartest thing you’ve said all morning.”

You’re probably thinking: Wait, you just charged in without a plan?

But Annabeth and I had been fighting together for years. We knew each other’s abilities. We could anticipate each other’s moves. I might have felt awkward and nervous about being her boyfriend, but fighting with her? That came naturally.

Hmm…that sounded wrong. Oh, well.

Annabeth veered to the giant’s left. I charged him head-on. I was still out of sword-reach when Cacus unhinged his jaw and blew fire.

My next startling discovery: flaming breath is hot.

I managed to leap to one side, but I could feel my arms starting to warm up and my clothes igniting. I rolled through the mud to douse the flames and knocked over a rack of women’s coats.

The giant roared. “Look what you’ve done! Those are genuine fake Prada!”

Annabeth used the distraction to strike. She lunged at Cacus from behind and stabbed him in the back of the knee—usually a nice soft spot on monsters. She leaped away as Cacus swung the caduceus, barely missing her. The silver tip slammed into the bulldozer and the entire machine turned to stone.

“I’ll kill you!” Cacus stumbled, golden ichor pouring from his wounded leg.

He blew fire at Annabeth, but she dodged the blast. I lunged with Riptide and slashed my blade across the giant’s other leg.

You’d think that would be enough, right? But no.

Cacus bellowed in pain. He turned with surprising speed, smacking me with the back of his hand. I went flying and crashed into a pile of broken stone cows. My vision blurred. Annabeth yelled, “Percy!” but her voice sounded as though it were underwater.

Move! Martha’s voice spoke in my mind. He’s about to strike!

Roll left! George said, which was one of the more helpful suggestions he’d ever made. I rolled to the left as the caduceus smashed into the pile of stone where I’d been lying.

I heard a CLANG! And the giant screamed, “Gah!”

I staggered to my feet. Annabeth had just smacked her shield across the giant’s backside. Being an expert at school expulsion, I’d gotten kicked out of several military academies where they still believed paddling was good for the soul. I had a fair idea how it felt to get spanked with a large flat surface, and my rump clenched in sympathy.

Cacus staggered, but before Annabeth could discipline him again, he turned and snatched the shield from her. He crumpled the Celestial bronze like paper and tossed it over his shoulder.

So much for that magic item.

“Enough!” Cacus leveled the staff at Annabeth.

I was still dizzy. My spine felt like it had been treated to a night at Crusty’s Water Bed Palace, but I stumbled forward, determined to help Annabeth. Before I could get there, the caduceus changed form. It became a cell phone and rang to the tune of “Macarena.” George and Martha, now the size of earthworms, curled around the screen.

Good one, George said.

We danced to this at our wedding, Martha said. Remember, dear?

“Stupid snakes!” Cacus shook the cell phone violently.

Eek! Martha said.

Help—me! George’s voice quivered. Must—obey—red—bathrobe!

The phone grew back into a staff.

“Now, behave!” Cacus warned the snakes. “Or I’ll turn you two into a fake Gucci handbag!”

Annabeth ran to my side. Together we backed up until we were next to the ladder.

“Our tag game strategy isn’t working so well,” she noticed. She was breathing heavily. The left sleeve of her T-shirt was smoldering, but otherwise she looked okay. “Any suggestions?”

My ears were ringing. Her voice still sounded like she was underwater.

Wait…under water.

I looked up the tunnel—all those broken pipes embedded in the rock: waterlines, sewer ducts. Being the son of the sea god, I could sometimes control water. I wondered…

“I don’t like you!” Cacus yelled. He stalked toward us, smoke pouring from his nostrils. “It’s time to end this.”

“Hold on,” I told Annabeth. I wrapped my free hand around her waist.

I concentrated on finding water above us. It wasn’t hard. I felt a dangerous amount of pressure in the city’s waterlines, and I summoned it all into the broken pipes.

Cacus towered over us, his mouth glowing like a furnace. “Any last words, demigod?”

“Look up,” I told him.

He did.

Note to self: When causing the sewer system of Manhattan to explode, do not stand underneath it.

The whole cavern rumbled as a thousand water pipes burst overhead. A not-so-clean waterfall slammed Cacus in the face. I yanked Annabeth out the way, then leaped back into the edge of the torrent, carrying Annabeth with me.

“What are you—?” She made a strangling sound. “Ahhh!”

I’d never attempted this before, but I willed myself to travel upstream like a salmon, jumping from current to current as the water gushed into the cavern. If you’ve ever tried running up a wet slide, it was kind of like that, except at a ninety-degree angle and with no slide—just water.

Far below I heard Cacus bellowing as millions, maybe even thousands of filthy gallons of water slammed into him. Meanwhile Annabeth alternately shouted, gagged, hit me, called me endearing pet names like “Idiot! Stupid—dirty—moron—” and topped it all off with “Kill you!”

Finally we shot out of the ground atop a disgusting geyser and landed safely on the pavement.

Pedestrians and cops backed away, yelling in alarm at our sewage version of Old Faithful. Brakes screeched and cars rear-ended each other as drivers stopped to watch the chaos.

I willed myself dry—a handy trick—but I still smelled pretty bad. Annabeth had old cotton balls stuck in her hair and a wet candy wrapper plastered to her face.

“That,” she said, “was horrible!”

“On the bright side,” I said, “we’re alive.”

“Without the caduceus!”

I grimaced. Yeah…minor detail. Maybe the giant would drown. Then he’d dissolve and return to Tartarus the way most defeated monsters do, and we could go collect the caduceus.

That sounded reasonable enough.

The geyser receded, followed by the horrendous sound of water draining down the tunnel, like somebody up on Olympus had flushed the godly toilet.

Then a distant snaky voice spoke in my mind. Gag me, said George. Even for me that was disgusting, and I eat rats.

Incoming! Martha warned. Oh, no! I think the giant has figured out—

An explosion shook the street. A beam of blue light shot out of the tunnel, carving a trench up the side of a glass office building, melting windows and vaporizing concrete. The giant climbed from the pit, his velour housecoat steaming, and his face spattered with slime.

He did not look happy. In his hands, the caduceus now resembled a bazooka with snakes wrapped around the barrel and a glowing blue muzzle.

“Okay,” Annabeth said faintly. “Um, what is that?”

“That,” I guessed, “would be laser mode.”

To all of you who live in the Meatpacking District, I apologize. Because of the smoke, debris, and chaos, you probably just call it the Packing District now, since so many of you had to move out.

Still, the real surprise is that we didn’t do more damage.

Annabeth and I fled as another laser bolt gouged a ditch through the street to our left. Chunks of asphalt rained down like confetti.

Behind us, Cacus yelled, “You ruined my fake Rolexes! They aren’t waterproof, you know! For that, you die!”

We kept running. My hope was to get this monster away from innocent mortals, but that’s kind of hard to do in the middle of New York. Traffic clogged the streets. Pedestrians screamed and ran in every direction. The two police officers I’d seen earlier were nowhere in sight, maybe swept away by the mob.

“The park!” Annabeth pointed to the elevated tracks of the High Line. “If we can get him off street level—”

BOOM! The laser cut through a nearby food truck. The vendor dove out his service window with a fistful of shish kebabs.

Annabeth and I sprinted for the park stairs. Sirens screamed in the distance, but I didn’t want more police involved. Mortal law enforcement would only make things more complicated, and through the Mist, the police might even think Annabeth and I were the problem. You just never knew.

We climbed up to the park. I tried to get my bearings. Under different circumstances, I would’ve enjoyed the view of the glittering Hudson River and the rooftops of the surrounding neighborhood. The weather was nice. The park’s flower beds were bursting with color.