“I want to use the dam water fountain,” Grover said.
“And . . .” Thalia tried to catch her breath. “I want to buy a dam T-shirt.”
I busted up, and I probably would’ve kept laughing all day, but then I heard a noise:
“Moooo.”
The smile melted off my face. I wondered if the noise was just in my head, but Grover had stopped laughing too. He was looking around, confused. “Did I just hear a cow?”
“A dam cow?” Thalia laughed.
“No,” Grover said. “I’m serious.”
Zoë listened. “I hear nothing.”
Thalia was looking at me. “Percy, are you okay?”
“Yeah,” I said. “You guys go ahead. I’ll be right in.”
“What’s wrong?” Grover asked.
“Nothing,” I said. “I . . . I just need a minute. To think.”
They hesitated, but I guess I must’ve looked upset, because they finally went into the visitor center without me. As soon as they were gone, I jogged to the north edge of the dam and looked over.
“Moo.”
She was about thirty feet below in the lake, but I could see her clearly: my friend from Long Island Sound, Bessie the cow serpent.
I looked around. There were groups of kids running along the dam. A lot of senior citizens. Some families. But nobody seemed to be paying Bessie any attention yet.
“What are you doing here?” I asked her.
“Moo!”
Her voice was urgent, like she was trying to warn me of something.
“How did you get here?” I asked. We were thousands of miles from Long Island, hundreds of miles inland. There was no way she could’ve swum all the way here. And yet, here she was.
Bessie swam in a circle and butted her head against the side of the dam. “Moo!”
She wanted me to come with her. She was telling me to hurry.
“I can’t,” I told her. “My friends are inside.”
She looked at me with her sad brown eyes. Then she gave one more urgent “Mooo!,” did a flip, and disappeared into the water.
I hesitated. Something was wrong. She was trying to tell me that. I considered jumping over the side and following her, but then I tensed. The hairs on my arms bristled. I looked down the dam road to the east and I saw two men walking slowly toward me. They wore gray camouflage outfits that flickered over skeletal bodies.
They passed through a group of kids and pushed them aside. A kid yelled, “Hey!” One of the warriors turned, his face changing momentarily into a skull.
“Ah!” the kid yelled, and his whole group backed away.
I ran for the visitor center.
I was almost to the stairs when I heard tires squeal. On the west side of the dam, a black van swerved to a stop in the middle of the road, nearly plowing into some old people.
The van doors opened and more skeleton warriors piled out. I was surrounded.
I bolted down the stairs and through the museum entrance. The security guard at the metal detector yelled, “Hey, kid!” But I didn’t stop.
I ran through the exhibits and ducked behind a tour group. I looked for my friends, but I couldn’t see them anywhere. Where was the dam snack bar?
“Stop!” The metal-detector guy yelled.
There was no place to go but into an elevator with the tour group. I ducked inside just as the door closed.
“We’ll be going down seven hundred feet,” our tour guide said cheerfully. She was a park ranger, with long black hair pulled back in a ponytail and tinted glasses. I guess she hadn’t noticed that I was being chased. “Don’t worry, ladies and gentlemen, the elevator hardly ever breaks.”
“Does this go to the snack bar?” I asked her.
A few people behind me chuckled. The tour guide looked at me. Something about her gaze made my skin tingle.
“To the turbines, young man,” the lady said. “Weren’t you listening to my fascinating presentation upstairs?”
“Oh, uh, sure. Is there another way out of the dam?”
“It’s a dead end,” a tourist behind me said. “For heaven’s sake. The only way out is the other elevator.”
The doors opened.
“Go right ahead, folks,” the tour guide told us. “Another ranger is waiting for you at the end of the corridor.”
I didn’t have much choice but to go out with the group.
“And young man,” the tour guide called. I looked back. She’d taken off her glasses. Her eyes were startlingly gray, like storm clouds. “There is always a way out for those clever enough to find it.”
The doors closed with the tour guide still inside, leaving me alone.
Before I could think too much about the woman in the elevator, a ding came from around the corner. The second elevator was opening, and I heard an unmistakable sound— the clattering of skeleton teeth.
I ran after the tour group, through a tunnel carved out of solid rock. It seemed to run forever. The walls were moist, and the air hummed with electricity and the roar of water. I came out on a U-shaped balcony that overlooked this huge warehouse area. Fifty feet below, enormous turbines were running. It was a big room, but I didn’t see any other exit, unless I wanted to jump into the turbines and get churned up to make electricity. I didn’t.
Another tour guide was talking over the microphone, telling the tourists about water supplies in Nevada. I prayed that Thalia, Zoë, and Grover were okay. They might already be captured, or eating at the snack bar, completely unaware that we were being surrounded. And stupid me: I had trapped myself in a hole hundreds of feet below the surface.
I worked my way around the crowd, trying not to be too obvious about it. There was a hallway at the other side of the balcony—maybe some place I could hide. I kept my hand on Riptide, ready to strike.
By the time I got to the opposite side of the balcony, my nerves were shot. I backed into the little hallway and watched the tunnel I’d come from.
Then right behind me I heard a sharp Chhh! like the voice of a skeleton.
Without thinking, I uncapped Riptide and spun, slashing with my sword.
The girl I’d just tried to slice in half yelped and dropped her Kleenex.
“Oh my god!” she shouted. “Do you always kill people when they blow their nose?”
The first thing that went through my head was that the sword hadn’t hurt her. It had passed clean through her body, harmlessly. “You’re mortal!”
She looked at me in disbelief. “What’s that supposed to mean? Of course I’m mortal! How did you get that sword past security?”
“I didn’t— Wait, you can see it’s a sword?”
The girl rolled her eyes, which were green like mine. She had frizzy reddish-brown hair. Her nose was also red, like she had a cold. She wore a big maroon Harvard sweatshirt and jeans that were covered with marker stains and little holes, like she spent her free time poking them with a fork.
“Well, it’s either a sword or the biggest toothpick in the world,” she said. “And why didn’t it hurt me? I mean, not that I’m complaining. Who are you? And whoa, what is that you’re wearing? Is that made of lion fur?”
She asked so many questions so fast, it was like she was throwing rocks at me. I couldn’t think of what to say. I looked at my sleeves to see if the Nemean Lion pelt had somehow changed back to fur, but it still looked like a brown winter coat to me.
I knew the skeleton warriors were still chasing me. I had no time to waste. But I just stared at the redheaded girl. Then I remembered what Thalia had done at Westover Hall to fool the teachers. Maybe I could manipulate the Mist.
I concentrated hard and snapped my fingers. “You don’t see a sword,” I told the girl. “It’s just a ballpoint pen.”