Emily Windsnap and the castle in the mist.

Liz Kessler.

It's midnight, and as light as day.

A full moon shines down on the ocean, making the waves dance as they skirt the edges of the tiny island, lapping on jagged rocks and stony beaches.

A chariot glides through the sea, tracing a circle around the island. Solid gold and adorned with jewels on every side, the chariot is pulled by dolphins, each decorated with a row of diamonds and pearls along its back and head.

Inside the chariot sits the king of all the oceans: Neptune, grander than ever, a chain of sparkling jewels around his neck, his gold crown glinting above his white hair, his trident by his side. His green eyes shine in the moonlight as he looks across at the island. He is waiting for his bride to appear from the castle that stands above the rocks, half hidden by mist, its dark windows gleaming in the bright night sky.

"Go around again!" he demands, his voice booming like thunder. His words send ripples bouncing away from the chariot. The dolphins draw another circle around the island.

And then she is there, smiling as she steps toward the water's edge, her eyes meeting his, their gaze so fierce it almost brings the s.p.a.ce between them to life. A bridge between their two worlds.

A small flock of starlings approaches the water as she does, circling the air above her head like a feathered crown. Twisting her head to smile up at them, she holds out a hand. Instantly, one of the birds breaks off from the circle and flies down toward her open palm. Hovering almost motionless in the air, it drops something from its claw into her palm. A diamond ring. As the woman closes her hand around the ring, the starling rejoins the other birds and they fly away into the night, slinking across the sky like a giant writhing snake.

"I give you this diamond to represent my love, as great as the earth itself, as firm as the ground on which I stand." The woman flicks back shiny black hair as she reaches out toward the chariot to place the ring on Neptune's finger.

A twist of the trident, and a dolphin swims forward. As it bows down to Neptune, it reveals a pearl ring, perfectly balanced on its brow. Neptune takes the ring. Holding it out in his palm, he speaks softly. "And with this pearl, I offer you the sea, my world, as boundless and everlasting as my love for you." He slides the ring onto her finger. "This is a most enchanted moment. A full moon at midnight on the spring equinox. This will not happen for another five hundred years. It is almost as rare as our love."

She smiles at him, her white dress wet at the bottom where she stands in the sea by his chariot.

Holding his trident in the air, Neptune continues. "These rings may only ever be worn by two folk in love a" one from the sea, one from land a" or by a child of such a pair. As long as they are so worn, no one can remove them."

"No one can even touch them," the woman says.

Neptune laughs. "No one can even touch them," he says. Then he holds his other hand up, palm facing the woman. She does the same and their arms form an arch, the rings touching as they clasp hands. A hundred stars crackle in the sky above them, bursting into color like fireworks. "When the rings touch like this," Neptune continues, "they will undo any act born of hatred or anger. Only love shall reign," he says.

"Only love," she repeats.

Then he spreads his arms out in front of him. "At this moment, night and day are equal, and now, so too are earth and sea. For as long as we wear these rings, the symbols of our marriage, there will always be peace and harmony between the two worlds."

With a final wave of his trident, Neptune reaches out to help the woman into the chariot. Hand in hand, they sit close together, her long dress flowing to one side of the chariot, his jewel-encrusted tail lying over the other side.

The dolphins lift the reins and the chariot glides silently off, taking its royal owners away to begin their married life together.

"Emily! I won't tell you again."

I opened an eye to see Mom pulling back the curtain across the porthole in my bedroom. Outside, an oval moon hung low in a navy sky. Almost full, I thought automatically. We'd been learning about the moon's cycle at school.

"It's still night," I complained as I pulled the quilt over my face and snuggled back into my pillow.

"It's half past seven," Mom replied, perching on the edge of my bed. She folded the quilt back and kissed my forehead. "Come on, sweet pea," she said. "You'll be late for school." As she got up, she added under her breath, "Not that you'd miss much if you were. They haven't exactly taught you anything useful at that place so far."

She'd left the room before I had a chance to reply.

I let out a heavy sigh as I lay in bed, looking up at the ceiling. Mom seemed to be really down lately. That was the third time she'd grumbled about something in the last week. Personally, I couldn't see what there was to complain about. We were living on a beautiful secret island: Mom, Dad, and me, all together on an elegant old wooden ship half sunk in the golden sand and sparkling water that surround the whole island. Merfolk and humans, together in peace.

I realize that last part isn't necessarily a requirement in everyone's ideal living situation, but it comes in handy when your mom's a human, your dad's a merman, and you're half-and-half.

I pulled my bathing suit on and joined Mom at the breakfast table. As with everything else in our home, the table lay on a slant, so I held on to my cereal bowl as I ate.

Dad swam up to the trapdoor next to my seat and pulled himself up to kiss me on the cheek. "Morning, my little starfish," he said with a smile. "Ready for your ocean studies test?"

"Test me!" I said.

Dad scratched his head. "How big can a giant j.a.panese spider crab grow?"

"Ten feet," I said instantly.

"Very good. Hm. What color is a banded b.u.t.terfly fish?"

"Black and silver. Too easy!"

"Too pointless, more like," Mom said under her breath. What was wrong with her?

Dad turned to her with a frown. "Not again!" He sighed. "What is the matter with you? Don't you want our daughter to do well at school?"

"I'm sorry," she said, reaching down for Dad's hand. "It's just . . ."

"What? What is it? She's learning a lot; she's enjoying herself, getting good grades. I couldn't be more proud." Dad smiled at me as he talked. I smiled back.

Dad and I hadn't gotten along all that well when we first came to Allpoints Island. I mean, we didn't get along badly; it just wasn't easy. I'd spent most of my life without him, and we didn't really know what to talk about, or where to start.

I didn't know he existed at all till recently. It was only a few months ago that I'd even found out about myself a" that I became a mermaid when I went into water. It terrified me in the beginning. The first time it happened, I didn't know what was going on. It was in a school swimming lesson, of all places. But then I got used to it, and I'd sneak out to swim in the sea at night. That's how I met my best friend, Shona. She's a mermaid too. A real, full-time one. She helped me find my dad. When I sneaked into Neptune's prison and saw him for the first time that was the best day of my life.

I guess it all took a little getting used to. But the last few weeks had been fantastic, once all the trouble with the kraken was sorted out. That's the most horrific, fearsome sea monster in the world, and I accidentally woke it up!

Since then, Dad and I had been out swimming together every day, exploring the golden seabed around Allpoints Island, racing against the multicolored fish that fill every stretch of sea around here, playing tag among the coral. Dad was officially the BEST dad in the world.

"That's just it," Mom was saying. "You couldn't be more proud. And you have every right to feel proud. Yes, Emily's coming along in leaps and bounds in . . ." She paused to reach over to the pile of textbooks I'd brought home the previous day. I loved all my schoolbooks. They weren't like any schoolbooks I'd ever had before, that's for sure! For one thing, they were all made from the coolest shiny materials, or woven with seaweed and decorated with sh.e.l.ls and pearls. And, for another, they were in the swishiest subjects! School had never been so much fun.

". . . Seas and Sirens," Mom read from the top one. She picked out a couple more books from the pile. "Or Sailing and Stargazing, or Hair Braiding for Modern Mermaids. I mean!"

"You mean what?" Dad asked, his voice coming out pinched and tight. "Why shouldn't she learn about these things? It's her heritage. What exactly don't you like about it, Mary?"

That's when I knew something was really wrong. No one ever calls my mom Mary, least of all Dad. Most people call her Mary P. Her middle name's Penelope, and Dad's always called her Penny a" or his lucky Penny, when they're being particularly gooey. Which they hadn't been for a while, now that I thought about it. And while I was thinking about it, I guess Mom had a point. I mean, don't get me wrong. I loved all my new school subjects. But maybe I did sometimes miss some of my old subjects, just a tiny bit. Or just English, perhaps. I used to love writing stories. I even liked spelling tests! That's just because I was good at them.

"What's wrong," said Mom, "is that while you may be happy for your daughter to learn nothing more than how to brush her hair nicely and tell the time by looking at the clouds, I'd like my daughter to get a real education."

"*My daughter,' *your daughter'? You make it sound as if she's two different people," Dad said. Below the floor I could see the water swishing around as he swirled his tail angrily. It splashed up onto the kitchen floor. Something swished and swirled inside me too, stirred up by his words. Was it true? Was I really two different people?

"Yes, well, maybe she is," Mom snapped, picking up a dish towel and bending down to wipe the floor. They were right. I wasn't like either of them. I was made up of two halves that didn't match. The swirling inside me doubled.

Then Mom glanced up at me and her face softened. "I mean, of course she's not. She's not two different people at all. It's not Emily's fault." Mom smiled at me, reaching up to hold my hands. I s.n.a.t.c.hed them away, turning my face at the same time so I couldn't see the hurt look in her eyes. That's one thing I absolutely can't stand. Her words didn't do much to soothe me, either.

And, anyway, it wasn't fair. She wasn't being fair. I'd never enjoyed school this much in my life! OK a" so maybe it would be nice to write stories sometimes, but so what if I wasn't learning social studies and science or fractions and French? Who said there was any point to those either? Was I ever really going to need to know how much John earns in a week if he gets 4 percent commission and 3 percent interest? Surely learning about my surroundings was more important. Knowing which fish were the most dangerous and which were almost friendly. Learning how to look and act like other mermaids, like a real mermaid. Even if I did feel a little silly perching on a rock combing my hair sometimes, at least I was learning how to fit in. Didn't Mom care about those things? Didn't she want me to be happy?

I went on eating my breakfast.

Mom drew a breath. "It's just that it's two different worlds," she said in a quiet voice. "And I sometimes wonder if they're just too different. I mean, look at my life here. What do I do all day? Sunbathe, comb my hair, maybe go to synchro swim a couple of times a week. This isn't a life for me, Jake. I want more than this."

She'd been saying things like this quite a bit lately. Only last week she'd complained that there was too much ocean and not enough land, and that it made her feel a bit stranded and lonely. I hadn't paid much attention at the time. Perhaps I really should have.

No one spoke for ages. Mom and Dad stared at each other. I'd just taken a spoonful of cereal and didn't want to chew in case it crunched really loudly, so I sat there with my mouth full of cornflakes and milk, waiting for one of them to say something.

"We'll talk about this later. I need to go out," Dad said eventually, and I swallowed my mouthful. It was too soggy to chew by then, anyway.

Dad left so quickly he didn't even give me a kiss. Not that I was bothered. I mean, I am twelve. I'll be thirteen in a couple of months. It's not as if I need my dad to kiss me good-bye when he goes out!

But. Well, it showed something. Maybe this was all my fault. It was only because of me that they had to try to bring the two worlds together at all. That and the fact that they loved each other, of course. But maybe they didn't anymore. Maybe they'd grown away from each other so much in the twelve years they'd been apart that they didn't love each other at all now and had to stay together just because of me. And maybe they both hated it, and hated each other, and in the end they'd both end up hating me too. And now Mom didn't even like her life anymore!

A strange, cold feeling started to spread inside me, creeping around my body, seeping into my bones. Only weeks ago, we'd been given a new start on this island. A dream come true. Everything we'd ever wanted. But what if it wasn't a dream come true at all? What if it was going to turn into a nightmare, as so many of my dreams did? Or used to.

A small voice inside my head said I was probably blowing it out of proportion. It's just an argument, I reasoned with myself. All married couples argue. And I knew I had a vivid imagination. My teachers had always told me so. Part of me knew I was overreacting. But the other part of me couldn't stop worrying. And that part seemed to have a louder voice.

Perhaps it was only a matter of time before Mom and Dad decided to abandon ship and not bother being together at all. Then what? Would I have to choose between them? Would either of them even want me if it was all because of me that their marriage had gone wrong? They'd probably fight each other not to have me.

I tried to shake the thoughts from my mind as I got ready for school. The ocean studies test was that afternoon and I was determined to do well. I'd show Dad that I really could follow in his footsteps, or wash in his wake, as he liked to say.

The thought cheered me up, and I even allowed myself to smile as I packed my books. Till another thought chased the smile off my face like a shark chasing off a shoal of unsuspecting bar jacks.

The better I did in my mermaid lessons, the less time I was spending on land with Mom doing what she liked. The closer I got to Dad, the further away I moved from her. Now that I thought about it, I wasn't surprised she was unhappy. I'd been so busy getting to know Dad, I'd hardly done anything with Mom. I should have listened when she'd told me she was lonely. I should have made Dad listen too. Why hadn't I?

I didn't have an answer. So perhaps she was right after all. Perhaps the two worlds were simply too different to coexist. Perhaps my parents weren't meant to be together at all.

I slunk away from the boat, dropping into the water without even saying good-bye, too miserable to speak, too scared to think.

As I dived down, my worries melted away, falling off me as if I were shedding a skin.

My legs felt as heavy as concrete, for a moment weighing me down in the water as they stiffened. It didn't bother me, though. I was used to it. In fact, it was the best feeling in the world because I knew what was going to happen next.

My legs joined together, sticking to each other so tightly it was as though someone were taping them together and winding bandages around and around them.

And then my tail formed.

I stretched out like a cat and watched as the bottom half of my bathing suit faded into shiny silver scales, glinting and sparkling and spreading farther and farther as my tail flickered and swished to life. I would never get bored of that feeling. It was like having been shut up in a box and then taking the lid off and throwing the sides open and being told you could move wherever you wanted, however you wanted. It was like having the whole world opened up to you.

I hovered in the water, flicking my tail to make sure it had fully formed. It glinted purple and green as I batted away a pair of tiny silver fish swimming along its side. Every toss sent little bubbles dancing up to the surface.

I let myself sigh happily. Everything felt better while I was a mermaid.

I swam along the tops of the coral, glancing down at the underwater forests as I made my way to school.

Bright green bushes waved at me as I sailed over them; rubbery red tubes nodded and bobbed from side to side. A pair of golden sea horses weaved their way around long trails of reeds that swayed and dipped in the current, their tails entwined. Gangs of paper-thin fish with bright yellow tails and round-bellied blue fish with black eyes all darted purposefully around me. I tried to remember what they were all called, just in case it came up on the ocean studies test, but they weren't familiar. There was something new to see here every day. I could never tire of Allpoints Island, even if Mom had had enough of the place.

I came to a cl.u.s.ter of rocks at the edge of a tunnel and waited. School was at the other end of the tunnel, in the Emerald Caves. Shona and I had started meeting up here so we could go in together.

A few of the others from my cla.s.s smiled as they went past me. Most of the cla.s.s were mermaids. There were a few merboys and two human boys and two girls. I hadn't gotten to know that many of the others yet, although Shona and I hung around quite a lot with two other mermaids, Althea and Marina. I was the only one who was half-and-half. The only semi-mer. There was a name for us, even if there were hardly any of us in existence!

I'd gotten used to being the only one, I suppose, even though I sometimes wished I weren't. It would just be so cool to have someone else who knew what it felt like to transform like I did. It would be better than cool, in fact. It might help me feel that I fit into the world somewhere, that I wasn't quite such a total misfit.

Well, there was one person. The only other one like me I'd ever met, but he hardly counted. For one thing, he was an adult; for another, he was the most untrustworthy, sly person you could ever meet: Mr. Beeston. My mom's so-called friend. Who'd turned out to be so much of a friend that he'd spent years spying on us and reporting back to Neptune!

Anyway, that was all history now. At least he wasn't trying to drug us or lie to us anymore.

"Emily!" A familiar voice tinkled across to me, sending Mr. Beeston far from my mind. Shona!

She swam toward me, clutching her tote bag against her side. It was silver and gold and covered in tiny pink sh.e.l.ls. Shona always had the prettiest things. She was the kind of mermaid you imagine mermaids to be, all girly and sparkly, with shiny long blond hair. Not like me. I was trying to grow my hair, and it was past my shoulders now, but it still never looked anything like Shona's: sleek and beautiful and, well, mermaidlike, I guess.

"Have you studied?" she asked excitedly as we followed behind a group of younger mermaids with their moms. Holding hands with one another as they swam, they raced ahead to their cla.s.s, leaving their moms chatting as they glided along behind them.

"Dad tested me this morning," I replied. "Think I got them all, but I don't know if I've learned the right fish."

"We have till this afternoon, anyway," Shona said. "And you know what this morning is, don't you?"

I smiled as I answered her. "Beauty and Deportment. What else?"

B&D was Shona's favorite cla.s.s. Nothing made her happier than learning a new way to style her hair or get the best shine out of her tail or swim with perfect elegance. I was more interested in shipwreck studies and siren stories, but the whole idea of mermaid school was still so new to me that I didn't really mind what we did or what we learned, as long as it wasn't long division!

We swam on down the channel. You had to feel your way along the walls as you swam along the first part. My heart rate always sped up here. The walls, slimy and wet and cold, set off too many memories of what had happened when I'd discovered the kraken in a slimy, dark tunnel.

We soon rounded a corner, and the tunnel opened up again, growing lighter and filling with color. I smiled away the memories. I never told Shona how I felt going along that channel. I always wondered if she felt the same way, but it was something we never talked about. She'd been with me when I woke the kraken and was probably as eager as I was to forget about it.

We b.u.mped into Althea and Marina as we reached the fork that led down to our cla.s.s. Marina swam hurriedly over to us, her long gold tail flicking rapidly from side to side. "Hey, I overheard Miss Finwave talking to one of the moms on the way in," she said with a grin. "And guess what?"

Shona's eyes opened wide, glistening even more than they usually did. "What?" she replied in the same excited tone as Marina's.

"We're going on a B and D outing!"

"Swishy!"

Althea turned to me. I must have looked puzzled. "It means we get to go out exploring the reef and the rocks," she explained.

"What, you mean like when we studied the creeks through the island?"

She shook her head. "That was a geography reef trip. More scientific. This one will probably have something to do with looking for material to make new hairbrushes or finding the perfect rocks to sit on the edge of." Althea pretended to yawn as she spoke.

Marina punched her arm and laughed. "Come on, you know you love it," she said.

Althea grinned back at her friend. "Yeah, I suppose it beats this afternoon's OS test."

We went on talking as we followed the fork that led up to our cla.s.sroom. It still took my breath away every time I arrived here. A cave filled with smooth greeny-blue water. Above, shimmering stalact.i.tes drooped from the high ceiling in thin folds like pterodactyls' wings or pointed down to the pool like sharp bundles of arrows frozen in midflight. All around us, blue and green and purple lights glimmered and winked, dancing on the surface of the deep pool. We swam into the cave, taking our places among the rest of the cla.s.s.