I'm alone in the girls' bedroom. Pickles is in the common room with Fintan. Lily-Bella is still at the dance, and Shelly is still not back. I'm honestly starting to worry.

It's stuffy in our room, and the smell of perfume is overwhelming. I open the window. Outside, owls hoot, and the wind whistles past the cabin. I want to take a quick shower and go to sleep, but first I need something to wear to bed. We left our room pretty messy, so I have to rummage around to find something.

Finally, I see a hint of turquoise peeking out from beneath the pink. Yay! Something not pink! Now, where are my underpants?

Through the door, I hear Pickles giggle. When we returned to the cabin after the dance, I tried to get her to go to bed and get some sleep, but she wanted to ... um ... talk to Fintan a little longer. Fintan seems pretty nice. He heated a mug of water with his hands and made Pickles bergamot tea. I asked him about his abilities with fire, and he said he'd always had them. Like a baby fry being able to swim or a fawn being able to walk right after its birth, controlling fire is something he apparently does naturally.

I take a long shower, worrying about Pierce the whole time. I hope he doesn't get caught. Should I check on him? But he's smart and fast and has better hearing than a dolphin. And I'm so exhausted, I'd probably do something stupid that would get us both in trouble.

The warm water in the shower is bliss, and I wash my hair with some of Lily-Bella's shampoo. It's a scent called jasmine, and it's kind of nice. Afterward, my hair is smooth and slick and sticks to my body like thick blades of kelp.

I put on my underwear and throw on the mustard-stained sweatshirt. But who's going to see me anyway? I crawl between the cool sheets on my bed. My eyelids are heavy, and the back of my eyeballs ache. The air is smoky and dry from the fire blazing in the common room, and I'm lulled to sleep by the low, even murmur of Fintan's voice.

Pierce and I are holding hands and swimming on the surface of the open ocean. The salmon sky is streaked with gray clouds; the sun ahead of us is a pinprick of light on the horizon. It seems to get further away the faster we swim.

A pod of bottlenose dolphins joins us, flanking us like sentinels. They have sleek grey skin and permanent smiles. They're chattering in their native Dolphin tongue. I can pick up a few words. They are commenting on my hair. (Dolphins are a little jealous of mermaid hair. Don't know why. It would look totally ridiculous on a dolphin.)

A shimmering wave of anchovies swarms within our ranks. So do bat rays, eels, and even sharks. In the air, a flock of gulls tracks our movement.

The headwind picks up, slowing our progress. The ocean water swells and chops and turns into the same oily, freaky kaleidoscope of color that I saw inside the cave.

"Pierce, we have to get out of here!"

The dolphins bite the ends of my hair and tug. "Hey, that hurts," I say telepathically. Pierce's hand tightens around mine, but they pull harder. "No!" I scream as Pierce's hand slides away. "Pierce!"

The dolphins let go of my hair and poke my body with their snouts. "Ouch!"

Now they're arguing.

"You said she was smart!"

"She is."

"Is not. She's as sentient as a piece of driftwood."

"She's sleeping."

"Poke her harder. Poseidon's spear! If a shark came in here looking for dinner, she'd be halfway through its digestive tract by now."

"Sharks don't come on land."

"It was a metaphor!"

"Waverly? Waverly? Wake up."

I drag myself out of what I now realize is a dream, but my heart is still racing. The poking continues, but it's obviously not dolphins. In fact, something is walking on the bedspread. Rodents? Urgh! "Hey!" I sit up and start swatting. Wait, the rodents called me by name? That's not normal.

"What in Poseidon's name?" I say.

"Waverly! Waverly! It's me, Beau."

"Beau?"

Two tiny horses trot across the covers, one coral, the other a silvery-blue.

"Yep!"

"Beau," I telepathically say. "But you're a seahorse."

"Told you she wasn't that bright," the blue seahorse snaps in an abrasive tone.

"Shush, Olga. She saved my life."

"I am totally confused," I say. "But it's great to see you! Who is your friend?"

Beau hops onto my hand and does a little bow. "Hello, Waverly. May I introduce you to my wife? This is Olga." He gives me a significant look that translates to: 'See what I mean? This is why I was hiding in a poisonous cave.' I almost understand now.

"We're merhorses," says Olga in a condescending voice.

"Merhorses? But there is no such thing as a merhorse."

Olga snorts. "Dumb as a shark," she says. "Merfolk think they're so special. Like they're the only magical, morphing sea creatures."

"That woman is so insensitive," Beau mutters. "Sorry, Waverly. We are merhorses—seahorses in water, land horses on, well, land. We try to keep a low profile because we have certain abilities we don't want other creatures to know about. We might be exploited."

"That's top-secret information, Beau," Olga hisses. "Need-to-know basis only. She's a total stranger."

"Olga, if you don't stop that right now, you're never getting another brood!"

Olga rears back and tries to look all threatening, but she's maybe three inches tall, so I can't help laughing.

"Look, Waverly, we don't have much time. Got about two hundred fingerlings back in the bay that need their crustacean dinner and a bedtime story, but we had to come to warn you about what we saw. I wanted to come alone, but Olga didn't believe I was rescued by a mermaid. She never believes anything I say."

"Wow, two hundred fingerlings! That's even worse than my parents!"

Olga paws the plaid bedspread and snorts. I ignore her.

"Start at the beginning, Beau. What happened?"

"After you left, Olga found me quite a way from the cave. She was pretty mad, because she'd been searching for me everywhere. She said it was time for me to get pregnant—no more excuses. So I told her we couldn't have more fry right now because of what's happening in the cave, and that it's affecting more and more of the bay, and the sharks are getting dumber, and the jellyfish are getting tangled in in their own tentacles, and the eelgrass is dying, and lots of other crazy things are happening. But as I said, she never believes anything I say, so she made me take her back to that horrible cave and show her."

"No, Beau. You didn't!"

"I did. And I saw something."

"What?"

"Humans. Those scubahumans. We've seen them before. They look ridiculous in those sharkskin suits and silly oversized flippers."

"What were they doing?"

"They lowered big containers into the water near the cave. Then they opened a place in the rock; I couldn't figure out how. It swung out like a door, but it was made to look like rock. They rolled the containers inside, shut it back up, so it looked like rock again, and swam to the surface, back to some boat."

"When did this happen?"

"I have no idea," Beau says. "No sense of time whatsoever."

"Right. I remember you telling me that."

"See, Olga. She believes me when I tell her something."

Olga glared at him. "Okay, you were telling the truth. I believe you. Can we go back now?"

"Did the containers have any markings on them?"

"No. They were plain and the color of dried seaweed. Waverly, can you help us stop these humans?" He looks at me sadly. "We love the bay, but we'll soon have to leave. As it is, we are moving farther and farther away from the cave to keep the little ones safe. Do you know how hard it'll be to move our entire family? Plus, there'll be a whole new ecosystem to learn. New schools. New predators. Most of the fry are too young to take their land form."

"I promise I'll stop them," I say to Beau.

"You are the nicest mermaid I've ever met," he says.

The door to the bedroom opens, and Pickles enters. "Baby horses!" she squeals.

Fintan follows her in. "Pickles, are you okay?"

"I'm fine. But look, Waverly has tiny horse pets. They are adorable."

"Tell her we are not pets," Olga snorts indignantly.

"They're not pets, Pickles. They are my friends, Beau and Olga."

"Why are you here?" Fintan asks them, speaking out loud.

"We were warning Waverly about the evil humans poisoning the bay. She's going to stop them. Could be dangerous, but I've seen her confront a shiver of great whites while bleeding. They swam away, cowering in fear!"

Something is strange. It seems like Beau is telepathically answering Fintan.

"Humans are poisoning the bay?" says Fintan.

"What?" says Pickles. "No!"

"We believe so," Beau says.

Beau is answering Fintan's question again. "Wait," I say telepathically. "You guys understand each other?"

"Guess so," Fintan says out loud.

I realize Fintan can hear my telepathic speech as well! "How is this possible?"

"Don't know," says Fintan. "I've never done it before."

"What haven't you done before?" says Pickles, putting her hands on her hips. "Who are you talking to, and what is going on with the water?"

No! Pickles and Fintan cannot get involved in this. It is too dangerous. "Pickles! It's nothing for you to worry about. My friends were leaving."

"I think Waverly will fight the humans contaminating the bay," says Fintan.

"Waverly Marie Fishwater, if you think you're going to do something dangerous without me, you are one crazy mermaid. I am your fairy godmother. When are you going to understand what that means?"

Ugh! She used my full name. So parental.

Lily-Bella floats into the room, yawning. Suddenly, her eyes brighten. "Merhorses!" she says. "I haven't seen a merhorse since I went on vacation with my family to Atlantis. It was one of those 'educational' trips your parents try to make sound cool. All those ancient artifacts. It was so boring. Except for the merhorses."

"I like her," says Olga.

"What's all the racket?" says Thunder Woolfson. His bulk fills the doorframe.

"Humans are poisoning the water," says Pickles, "and we will stop them."

"What was that, Pickles?" It's Pierce in the common room. He's okay!

Thunder steps into the room, making way for Pierce.

"You made it back!" I leap from the bed and jump into Pierce's arms. I kiss him. He tastes like strawberries, and his full lips are almost warm.

When we finally break the kiss, Pierce says, "I'm definitely going to leave more often. That was ..."

"I know," I say, grinning at him.

"Ugh, get a room," says Pickles.

"You're one to talk," I say.

"Yeah, I guess you're right." Pickles laughs. Fintan wraps his arms around her waist.

"From what I heard Pickles saying about the poisoned water, I guess everyone knows?" says Pierce.

"Yes, but I'm worried. I don't want to put my friends in danger."

"You're not doing anything to us," says Pickles. "We want to help, right, guys?"

Everyone talks at once. They all want to help! Warmth spreads through my body like a geothermal hot spring. This is when I realize all I've got on is my stained sweatshirt and underwear. But guess what? Right now, I don't even care.