Her arms are like hummingbird wings flitting through the water. She's almost a foot away from him. They reach the rocks. He flips right around, a smile visible when he breaks the surface just for show. My own gills burn.

"Will you stop pacing?" Marty pulls on my cargo shorts. "It isn't going to help."

Maybe not looking might somehow make this nauseous feeling go away. I pick the spot directly across from me where the herald tents are. Alone, while her future husband is racing my best friend, the Snow White mermaid lies on heaps of blankets. The servants who surrounded her moments ago are gathered at the edge of the lake. She leans her cheek on her fist, bored. That's when I see it. I mean, see her. In a second, her gray eyes glaze over with a black shadow and her lips mouth a single word, a word I can't even begin to guess the meaning of.

The crowd gasps and squeals as Layla speeds up. One, two, three, four strokes, and she's reached the other side of the sh.o.r.e.

Elias is only a second behind her, but it's clear to everyone watching that he's lost.

The court is a mess-girls, kids, fathers-laughing. My grandfather is still and pulls at the tip of his chin hair. He makes a motion to reach for something at his right, his trident, and then realizes it isn't there anymore.

Elias has lost. He's lost to a human girl, an intruder, and the court is laughing at him. I look for his fiancee, but she isn't there anymore, and I can't find her in the crowds of the court.

In the lake, Layla cries out and cringes. She has a cramp and grabs on to the rocky ledge. Kurt and Marty are weaving their way through to help pull her out of the water as Elias turns his bloodshot eyes on my friend. My Layla.

Brow tight, lips curled in a growl, hands outstretched for her neck, he is literally a creature rising from the lake to attack her. I can't say I do this without thinking. I think he's going to hurt her. I don't think about what this might do to my standing as a champion. I run and dive into the lake, close enough to him that my splash distracts him. Elias turns to me full on.

The shift comes naturally. It starts as a tingle in my spine, right where my tattoo is, and it travels all the way down. In two strokes I adjust to one tail movement instead of two kicking legs. One, two, and I have my arms around him. One under the right arm and one over his left shoulder. I squeeze him and he pushes hard against me, so we sink into the water.

He's physically stronger, and we go down, down, down. We hit against a wall, and I let go of him. He charges at me with arms outstretched, full speed, Superman underwater. We're locked in a wrestler's grip, forearm to forearm.

Something in me is awakening. I don't know what to call it. Instinct is too simple. It's older, more primal. It's more than defending a girl I'm possibly in love with; it's knowing that I can beat him. I push as hard as I can through the water. I can feel every fiber in my body, every bone in my tail, and he cannot overpower me. Something in me knows nothing can harm me. I am untouchable.

And then there is the darkness. We're so far from the surface that the light doesn't reach us anymore. He breaks my hold and hits me right on the jaw, sending me slamming against a boulder. His hands close around my neck so my gills can't take in water. I hold my breath, but it isn't enough. I wrap my tail around his, and even though I can't see his face, I can still see the whites of his eyes. His grip loosens, and his eyes roll back into his head. He lets go completely, falling down into the pitch-black. Did I do that? I couldn't have. I wouldn't know how.

My stomach contracts and there's that nauseous feeling again. My head feels like it's splitting open. I reach for Elias's hand and try to pull him up to the surface, but he's as heavy as he looks, and my muscles feel like elastic that's given out and snapped.

I shut my eyes against the throbbing pain in my head, and I know this is all happening because of her. I can see her face again. Smiling, waiting in the black coldness of my dreams, the silver mermaid. Waiting for a moment like this.

It's daylight.

I'm drooling all over my arm in Ancient History. The teacher, Mr. Van Oppen, leans his Hugh-Grant-looking self against the chalkboard. He has a funny accent I can't ever guess right and the kind of hair that flops everywhere when he runs his fingers through it.

The girls are crazy about him. I'm talking Indiana-Jones-writing-on-their-eyelids-and-hanging-around-after-cla.s.s-washing-the-eraser-board-for-him kind of crazy.

"And what year did Alexander the Great conquer all? Come on, now, it's not like it's in front of you on the reading a.s.signment from last night, hmm?"

Silence.

A sliver of light peers through the blinds and hits me right in the eyes. Mr. Van Oppen pulls on the string to make the shutters stay shut, and my eyes are unblinded. The lights in the cla.s.sroom are so bright that I can't imagine how I fell asleep in the first place.

He taps my desk with his long, skinny index finger.

"Mr. Hart?" He never calls anyone by their first name.

"'At the age of nineteen / He became the Macedon King / And he swore to free all of Asia Minor / By the Aegean Sea / In 334 B.C. / He utterly beat the armies of Persia'?"

"Very good, Mr. Hart. I see you've been listening to your Iron Maiden, hmm?"

The cla.s.s snickers.

"What made him a good king? Ms. Shea?"

Maddy sits with her legs up on the chair. She's wearing a tiara from her Sweet Sixteen party, which was really just me, her, Layla, and some of her drama club nerds at Ruby's on the boardwalk, because her mom wouldn't let her have a party. The tiara was my will-you-be-my-girlfriend gift, along with a few other things I fished out of my mom's junk trunk.

Maddy pops a big, green bubble-gum ball and rolls her eyes. "Down with kings! Alexander the Great was such a poser. Did he even fight? No. He just got people killed, and killed a whole bunch of other people who didn't even want to be ruled. He killed them right there and then-dead. Dead, dead."

My head pounds at the temples.

There's a knock on the door. Everyone looks at me, then at the door. Then me again.

I stand and b.u.mp into the desk next to mine. It's Layla's. She sits with her hands tied and propped on the desk. She has her head down like she doesn't want anyone to look at her face. "This is all your fault, Tristan. All your fault," she says.

"What the-" I grab her hands and start trying to undo the ropes, but every time I get one knot undone, another one pops up in its place.

Maddy gets up and out of her desk, and everyone goes, "Oooooooh."

She stands over me and says, "You always picked Layla over me. Now you got her dead. All you do is hurt people, Tristan Hart."

"The door, Mr. Hart. The door." Mr. Van Oppen walks around and sits on his desk. "Everyone else turn to page 1001, the future-the destruction of New York City by a little merman."

"Wh-"

"The door, Mr. Hart. Answer the door."

I can't shake the numbness spreading through my body. I turn the k.n.o.b, and when I open my eyes, the silver mermaid is there. She bares her shark teeth at me. The hallway is full of water. She moves her hands to try and grab me, but she can't breach the gla.s.s wall between us. I shut the door in her face and press my back against it.

Mr. Van Oppen stares at me with a furrowed brow and a crooked smile. "My, my. And here I was wondering what all the fuss was about. Hmm?"

When I breathe, I breathe hard.

Breathe like I haven't had any air in years. Layla's face is right over me. Her eyes are wet, and she wipes her hand across them. She brings her closed fist right down on my chest. Deja vu.

"Easy, girl," I hear Marty say.

"Where am I?"

"You're alive is what you are," Thalia says. She's in between shifts. Her deep green scales cover her b.r.e.a.s.t.s, and she's still wearing her puffy pink skirt. She's rubbing a black paste onto my chest where I've got more long red scratches.

"You're in the king's quarters," Kurt says from somewhere. I recognize the bed, the throne across the room, the empty stand where the trident used to be.

I stretch my arms out and feel the sheer blanket, too fine to be silk but the softest thing I've ever felt. Then I glance at Layla's face again and think of the kiss I stole from her. No way, her lips are definitely the softest.

But other memories push past that one-the silver mermaid, over and over again. She's here. She's somewhere on the island.

"Elias. That shark mermaid was down there. Where's my grandfather?"

"The king is calming the crowds," Thalia says. Her cuteness is replaced with that all-knowing, kick-a.s.s att.i.tude she doesn't always let peek through. s.h.i.t must be serious then.

"Elias's followers want your fins stripped on a platter."

"He's not back?" Of course he's not back. I remember him trying to choke me, then letting go and sinking into the abyss.

I can see it in their faces. They think it was me.

"I didn't kill him! I didn't!" I sit up, past the ache in my legs. "The last thing I remember is trying to reach for him. He was beating me, and then he just started-sinking. Then I got this feeling like my brain was ripping in half. I saw her, the silver mermaid. The shark mermaid from my dream! It's like she was inside my head."

Heavy footsteps enter the room. "Why didn't you tell me of this, Kurtomathetis?" The king's voice booms through the glittering stone walls.

"I didn't know-"

"Do you know how severe this is? How dangerous she is?" His face is red. His white mane curls wildly around his leathery shoulders.

"Wait, hold up. Rewind." I cross my hands in a T for time-out.

Grandfather walks over to his chair and sits. He slumps in his chair like he's beaten, like with every minute the trident is gone, more of the power he's held for centuries is washing away.

Layla and Thalia link arms at the edge of the bed. Marty leans against a wall, looking exactly the way he did when I first saw him, coffee straw and all.

"Tell me, Tristan," says the king, "when did the mermaid first come to you? What did she look like?"

"The day of the storm. I have zero memory of surviving except for this dream. She comes at me and attacks me, but this shark wearing some kind of helmet comes and saves me and drags me to sh.o.r.e."

"That explains the missing sharks on the guard," Kurt says.

"Indeed," my grandfather responds.

I tell them about all of my memories of her, the storm, the hospital, the dreams, the tunnel and pool right here in Toliss. "And when I was fighting Elias, it felt like she was trying to get into my mind. It's always like that, but there's a barrier and she can't ever break through. Who is she? What does she want with me?"

"She is my sister." My grandfather leans back on his tall golden chair and concentrates on the fireflies. "She is Nieve-a murderer and a deceiver. She's a sorceress and a traitor to the throne. When we were young, she killed my mother's newest babe out of jealousy. She was banished for two hundred years by my father, who feared the harpies' fury if he killed his own daughter. Then she was released, and she tried to become part of us again, but there was something rotting inside her, so she never could. Her blood is wrong, poison. When Father made me king in her stead as eldest, she killed him. So I locked her up below the sea, and she's been there for centuries."

"Why didn't you just off her?" Marty asks. I'm afraid my grandfather is going to turn around and drown him or just smack him, but he doesn't.

"Because I am an utter fool." He sighs long and hard. "I am foolish to think our kind can change. I am foolish to think that my people can find their way in this new world when I've clung to my father's tradition for so long. My father could not kill his own daughter, no matter how dreadful she was. She was still his. I knew I should've destroyed her when I took the throne. But there is no greater crime than killing your own family."

"But she killed her own sister and her father!" Layla yells.

"And she was punished. The Caves of Tartarus were supposed to contain her."

"Now she's out," I say, and I'm surprised at how even my voice is when I'm actually trembling. "So if my dreams weren't dreams, and someone was feeding her in the pool, then we're not the only ones who know she's out."

"Traitors in my own kingdom." Grandfather shakes his head. "Kurtomathetis, send guards to the Narrow Caves and report."

"Thalia, the two of you will remain with Tristan and guard his family." He looks at Layla and his face softens. "And friends, naturally."

"What should I do?" I stand with empty hands, unknowing. "She's definitely coming after me."

"When you were born I bound you. You have my protection. I released most of it so that you could shift into your true self, but my power is still there. Only when I am truly no longer king would she be able to harm you. Now that I no longer have the trident, my magics will ebb.

"You must find the trident. You should be king, as it is our family's right. No matter what blood you share. It is your birthright." He nods to the dagger slung over my shoulder.

"That was mine when I was your age, before I became king." I wonder about the things he's had to do with it, the things I'll have to use it for. "It was my father's and his and his and his. Well, I can go on for quite a long time. It was a gift from Triton."

"The Triton?" Marty goes, the excitement in his voice so rich that it's like he's the one getting the present.

"Yes, the Triton," Kurt answers irritably, returning from the tunnel.

"Son of Poseidon, G.o.d of the sea," Layla says.

The merpeople stare at her.

"What? My mom's Greek," she says, rolling her eyes.

My grandfather rummages through what looks like a bunch of junk. Now I know where my mom gets it from. "Now, where is that-ahh-yes, this'll do-Miss Layla?"

Layla rises slowly from the bed. She stands in front of him with damp curls and clothes. "Yes?"

"Because I am a merman of my word, and a king is only worth the promises he keeps, this is a token from my court. So that harm may never come to you by me or mine. I'd say you've earned it, quite surprisingly. My grandson is honored to have you as a companion."

Both our faces go red.

"You should tell him that," she says half jokingly.

He puts something in her palm, and she closes her fingers around it. She doesn't look at it, but she smiles her brilliant smile and thanks him.

"Marty, thank you again for the gift."

"Aw, King. No shiny dagger?"

My grandfather frowns at him for a moment before turning to us one more time. "Now, a fortnight will come and go, so I suggest you head back. As king, I cannot interfere with the champion, so I suggest you learn as much as you can from Kurtomathetis."

"I've got to grab some of our belongings," Thalia says. "Layla and I will meet you at the ship. King-" Just when I think she's going to bow down and curtsey, she runs up and gives him a tight hug. He holds her and smooths her hair like a father would to his own.

We start going down one tunnel together, but the girls make a right and we keep going straight toward a tiny white light.

When we've reached the mouth of the tunnel, it is dusk.

"It's a wondrous sight," says the king.

"Does this mean we get our summer back?" It's a tiny thing to look forward to.

My grandfather laughs. "Yes, the wall is down."

"But won't humans be able to detect it?"

He shakes his head. "The barrier is still there, but you can only see it if you're on the other side. Magics of that size are gradual."

Marty points to the sh.o.r.e. "Well, there's our ride. I can't wait to get this sand out of my-shoes."