“Look, this is going to sound weird. Do you know anything about Greek myths?”

“Like…the Minotaur and the Hydra?”

“Yeah, just try not to say those names when I’m around, okay?”

“And the Furies,” she said, warming up. “And the Sirens, and—”

“Okay!” I looked around the band hall, sure that Rachel was going to make a bunch of bloodthirsty nasties pop out of the walls; but we were still alone. Down the hallway, I heard a mob of kids coming out of the gymnasium. They were starting the group tours. We didn’t have long to talk.

“All those monsters,” I said, “all the Greek gods—they’re real.”

“I knew it!”

I would’ve been more comfortable if she’d called me a liar, but Rachel looked like I’d just confirmed her worst suspicion.

“You don’t know how hard it’s been,” she said. “For years I thought I was going crazy. I couldn’t tell anybody. I couldn’t—” Her eyes narrowed. “Wait. Who are you? I mean really?”

“I’m not a monster.”

“Well, I know that. I could see if you were. You look like…you. But you’re not human, are you?”

I swallowed. Even though I’d had three years to get used to who I was, I’d never talked about it with a regular mortal before—I mean, except for my mom, but she already knew. I don’t know why, but I took the plunge.

“I’m a half-blood,” I said. “I’m half human.”

“And half what?”

Just then Tammi and Kelli stepped into the band room. The doors slammed shut behind them.

“There you are, Percy Jackson,” Tammi said. “It’s time for your orientation.”

“They’re horrible!” Rachel gasped.

Tammi and Kelli were still wearing their purple-and-white cheerleader costumes, holding pom-poms from the rally.

“What do they really look like?” I asked, but Rachel seemed too stunned to answer.

“Oh, forget her.” Tammi gave me a brilliant smile and started walking toward us. Kelli stayed by the doors, blocking our exit.

They’d trapped us. I knew we’d have to fight our way out, but Tammi’s smile was so dazzling it distracted me. Her blue eyes were beautiful, and the way her hair swept over her shoulders…

“Percy,” Rachel warned.

I said something really intelligent like, “Uhhh?”

Tammi was getting closer. She held out her pom-poms.

“Percy!” Rachel’s voice seemed to be coming from a long way away. “Snap out of it!”

It took all my willpower, but I got my pen out of my pocket and uncapped it. Riptide grew into a three-foot-long bronze sword, its blade glowing with a faint golden light. Tammi’s smile turned to a sneer.

“Oh, come on,” she protested. “You don’t need that. How about a kiss instead?”

She smelled like roses and clean animal fur—a weird but somehow intoxicating smell.

Rachel pinched my arm, hard. “Percy, she wants to bite you! Look at her!”

She’s just jealous,” Tammi looked back at Kelli. “May I, mistress?”

Kelli was still blocking the door, licking her lips hungrily. “Go ahead, Tammi. You’re doing fine.”

Tammi took another step forward, but I leveled the tip of my sword at her chest. “Get back.”

She snarled. “Freshmen,” she said with disgust. “This is our school, half-blood. We feed on whom we choose!”

Then she began to change. The color drained out of her face and arms. Her skin turned as white as chalk, her eyes completely red. Her teeth grew into fangs.

“A vampire!” I stammered. Then I noticed her legs. Below the cheerleader skirt, her left leg was brown and shaggy with a donkey’s hoof. Her right leg was shaped like a human leg, but it was made of bronze. “Uhh, a vampire with—”

“Don’t mention the legs!” Tammi snapped. “It’s rude to make fun!”

She advanced on her weird, mismatched legs. She looked totally bizarre, especially with the pom-poms, but I couldn’t laugh—not facing those red eyes and sharp fangs.

“A vampire, you say?” Kelli laughed. “That silly legend was based on us, you fool. We are empousai, servants of Hecate.”

“Mmmm.” Tammi edged closer to me. “Dark magic formed us from animal, bronze, and ghost! We exist to feed on the blood of young men. Now come, give me that kiss!”

She bared her fangs. I was so paralyzed I couldn’t move, but Rachel threw a snare drum at the empousa’s head.

The demon hissed and batted the drum away. It went rolling along the aisles between music stands, its springs rattling against the drumhead. Rachel threw a xylophone, but the demon just swatted that away, too.

“I don’t usually kill girls,” Tammi growled. “But for you, mortal, I’ll make an exception. Your eyesight is a little too good!”

She lunged at Rachel.

“No!” I slashed with Riptide. Tammi tried to dodge my blade, but I sliced straight through her cheerleader uniform, and with a horrible wail she exploded into dust all over Rachel.

Rachel coughed. She looked like she’d just had a sack of flour dumped on her head. “Gross!”

“Monsters do that,” I said. “Sorry.”

“You killed my trainee!” Kelli yelled. “You need a lesson in school spirit, half-blood!”

Then she too began to change. Her wiry hair turned into flickering flames. Her eyes turned red. She grew fangs. She loped toward us, her brass foot and hoof clopping unevenly on the band-room floor.

“I am senior empousa,” she growled. “No hero has bested me in a thousand years.”

“Yeah?” I said. “Then you’re overdue!”

Kelli was a lot faster than Tammi. She dodged my first strike and rolled into the brass section, knocking over a row of trombones with a mighty crash. Rachel scrambled out of the way. I put myself between her and the empousa. Kelli circled us, her eyes going from me to the sword.

“Such a pretty little blade,” she said. “What a shame it stands between us.”

Her form shimmered—sometimes a demon, sometimes a pretty cheerleader. I tried to keep my mind focused, but it was really distracting.

“Poor dear.” Kelli chuckled. “You don’t even know what’s happening, do you? Soon, your pretty little camp in flames, your friends made slaves to the Lord of Time, and there’s nothing you can do to stop it. It would be merciful to end your life now, before you have to see that.”

From down the hall, I heard voices. A tour group was approaching. A man was saying something about locker combinations.

The empousa’s eyes lit up. “Excellent! We’re about to have company!”

She picked up a tuba and threw it at me. Rachel and I ducked. The tuba sailed over our heads and crashed through the window.

The voices in the hall died down.

“Percy!” Kelli shouted, pretending to be scared, “why did you throw that?”

I was too surprised to answer. Kelli picked up a music stand and swiped a row of clarinets and flutes. Chairs and musical instruments crashed to the floor.

“Stop it!” I said.

People were tromping down the hall now, coming in our direction.

“Time to greet our visitors!” Kelli bared her fangs and ran for the doors. I charged after her with Riptide. I had to stop her from hurting the mortals.

“Percy, don’t!” Rachel shouted. But I hadn’t realized what Kelli was up to until it was too late.

Kelli flung open the doors. Paul Blofis and a bunch of freshmen stepped back in shock. I raised my sword.

At the last second, the empousa turned toward me like a cowering victim. “Oh no, please!” she cried. I couldn’t stop my blade. It was already in motion.

Just before the celestial bronze hit her, Kelli exploded into flames like a Molotov cocktail. Waves of fire splashed over everything. I’d never seen a monster do that before, but I didn’t have time to wonder about it. I backed into the band room as the flames engulfed the doorway.

“Percy?” Paul Blofis looked completely stunned, staring at me from across the fire. “What have you done?”

Kids screamed and ran down the hall. The fire alarm wailed. Ceiling sprinklers hissed to life.

In the chaos, Rachel tugged on my sleeve. “You have to get out of here!”

She was right. The school was in flames and I’d be held responsible. Mortals couldn’t see through the Mist properly. To them it would look like I’d just attacked a helpless cheerleader in front of a group of witnesses. There was no way I could explain it. I turned from Paul and sprinted for the broken band room window.

I burst out of the alley onto East 81st and ran straight into Annabeth.

“Hey, you’re out early!” she laughed, grabbing my shoulders to keep me from tumbling into the street. “Watch where you’re going, Seaweed Brain.”

For a split second she was in a good mood and everything was fine. She was wearing jeans and an orange camp T-shirt and her clay bead necklace. Her blond hair was pulled back in a ponytail. Her gray eyes sparkled. She looked like she was ready to catch a movie, have a cool afternoon hanging out together.

Then Rachel Elizabeth Dare, still covered in monster dust, came charging out of the alley, yelling, “Percy, wait up!”

Annabeth’s smile melted. She stared at Rachel, then at the school. For the first time, she seemed to notice the black smoke and ringing fire alarms.

She frowned at me. “What did you do this time? And who is this?”

“Oh, Rachel—Annabeth. Annabeth—Rachel. Um, she’s a friend, I guess.”

I wasn’t sure what else to call Rachel. I mean, I barely knew her, but after being in two life-or-death situations together, I couldn’t just call her nobody.

“Hi,” Rachel said. Then she turned to me. “You are in so much trouble. And you still owe me an explanation!”

Police sirens wailed on FDR Drive.

“Percy,” Annabeth said coldly. “We should go.”

“I want to know more about half-bloods,” Rachel insisted. “And monsters. And this stuff about the gods.” She grabbed my arm, whipped out a permanent marker, and wrote a phone number on my hand. “You’re going to call me and explain, okay? You owe me that. Now get going.”

“But—”

“I’ll make up some story,” Rachel said. “I’ll tell them it wasn’t your fault. Just go!”

She ran back toward the school, leaving Annabeth and me in the street.

“Hey!” I jogged after her. “There were these two empousai,” I tried to explain. “They were cheerleaders, see, and they said camp was going to burn, and—”

“You told a mortal girl about half-bloods?”

“She can see through the Mist. She saw the monsters before I did.”

“So you told her the truth?”

“She recognized me from Hoover Dam, so—”