“I — I found it,” I said uncertainly.

  “Do you know what it is?” he asked.

  “Well, I — yes, I think I do.” Did he know what the ring was? Had he heard of Neptune, heard the story?

  “I’ve never seen it,” he said in a whisper. “Not the real one!”

  He fell silent, squeezing his mouth into a tight line and his eyes into slits while he thought. “All right,” he said, making up his mind about something. “We’ve got time. Come with me.”

  With that, he motioned to me to follow him to the door. Glancing down the corridor again, he nodded back to me. “Come on,” he said. “I want to show you something.”

  Aaron led me down a maze of corridors, scurrying quickly along till we came to a thick wooden door with bars and bolts across it. I followed him outside. Below us, the sea washed against rocks in the semidarkness. We ran around to the front of the castle and back inside through a small arched door. Following Aaron inside, I felt as though I were stepping further and further into a dream. Was any of this real? I mean, it felt real. The bricks of the castle were thick and hard, the rocks below were jagged and cold. But, still, something in the at mosphere made me feel as though I were floating, suspended just above reality, as if the castle really were floating on the mist.

  I closed the door behind me.

  We were in what looked like a small church. A tiny chapel in a remote wing of the castle. A few rows of seats all faced a raised platform at the front. Stained-glass windows were filled with pictures of biblical scenes.

  I followed Aaron to the raised platform. Right at the back of it there was a chest. He opened it. “Look,” he said, pointing inside.

  I peered into it. It contained a glass cabinet and, inside that — two rings. I looked closer at the one on the left, comparing it with the ring on my finger. It was identical!

  “But that’s — but they’re —”

  “Imitations,” he said. “My great-grandfather made them. From the descriptions, from the stories passed down through generation after generation.”

  “What stories? What descriptions?” I asked, my head spinning. “Do you mean about Neptune and Aurora?”

  “You know?” He gasped. “You know the story?”

  “That’s all I know,” I said. “Please, tell me.”

  Aaron moved away from the cabinet. “When Neptune and Aurora married, they cast a spell on their rings. While they were held by a human and merperson who were in love —”

  He glanced at me to check that I understood what he meant, to check that we were talking about the same thing. Maybe to check that I didn’t think he was ridiculous for believing in mermaids. I don’t only believe in them, I thought, I am one! But I wasn’t going to say that. Not yet. Not if it was just a story. Surely boys like him didn’t really believe in mermaids. Not that I’d ever met a boy quite like him. I don’t know if I’d met anyone like him before. All I knew was, I wanted to hear all about whatever he had to say.

  I nodded for him to continue.

  “As long as the rings were worn by one from land and one from the sea who loved each other, there would always be harmony between the two worlds,” he went on. “And there was. For the brief time the marriage lasted, there really was peace between land and sea. No ships were wrecked on rocks; no cargo was stolen; no sirens lured fishermen to their watery graves. Just peace. The two worlds thrived together. It was a magical time.”

  “And then she left him,” I said, remembering what Shona had said about her history lesson.

  Aaron’s green eyes bore down on me. “She what?” he asked angrily.

  “She — she left him?” I said more uncertainly. “Didn’t she?”

  “You know nothing!” he snapped. “Believing in such nonsense. How dare you?”

  I pulled at my hair, twisting it around my fingers. “I’m sorry,” I said. “I thought she did. I thought she broke his heart. I’m sorry.”

  “She did not leave him,” Aaron said firmly. “She loved him more than anything in the world. I’ll tell you what her love for him drove her to do.”

  I clamped my mouth shut. No more interruptions.

  “She loved him so much and believed so strongly in the magic they had created that she attempted the impossible. One night, she decided to show him what she could do out of love for him. You know what she did?”

  I shook my head.

  “She thought she could swim underwater to his palace. She believed their love was so great, it surpassed the normal laws of her human world. She believed she could become a mermaid. She drowned.”

  Neither of us spoke for a long time. As we stood in the silence, it felt as though the chapel were the whole world. As though the sea outside the window were there only for us. We were somehow at the center of everything, the center of something so important that — that what? I couldn’t tell.

  “It was her birthday. She’d wanted to surprise him as her present to him,” Aaron went on. “Her own birthday, and she wanted to surprise him. They’d only been married two years and a week.”

  “Go on,” I said softly.

  “When Neptune found her body, he took the ring from her and —”

  “I know this part,” I said quickly — even if it wasn’t exactly how Mr. Beeston had told it. I had to get it right this time, show Aaron he could trust me. “He tore the pearl ring from her finger and threw away his own ring, the diamond one.”

  “That’s right,” Aaron said. “And no one has ever seen the rings — till now.” He fell silent.

  “The kraken had Neptune’s ring,” I said. “I found it.”

  Aaron stepped toward me. “Emily, these rings can only be worn by certain folk.”

  “I know,” I said, swallowing.

  “A human and a merperson in love, or a child of such a pair . . .” His voice trailed off, and he looked at me, questioning.

  I didn’t reply. Finally I nodded.

  “I thought as much,” Aaron said, suddenly smiling. “You’re a semi-mer! You are, aren’t you?”

  “How did you know?”

  “You said you swam here through the tunnels. No human can swim underwater that far. It’s impossible.” He grinned wider. His whole face changed with his smile; it was like watching a two-dimensional picture come to life. “You found the diamond ring!” he said. “You really found it!”

  “Why is that so great?” I asked.

  Aaron led me back to the glass cabinet. “Look,” he said, pointing to an inscription in black, swirly writing beneath the rings.

  I read aloud. “‘When the rings touch, they will overrule any act born of hatred or anger. Only love shall reign.’”

  I looked up at Aaron. “I don’t understand,” I said.

  “There’s a curse,” he answered me, his face darkening. “It must be undone. And soon.”

  “What curse?” I shuddered. Did he know about the curse on me? Surely not — he couldn’t!

  Aaron brushed my question away with a flick of his hand. “We still need to find the pearl ring, though,” he said. “And that’s impossible.”

  “Who says it’s impossible? I found this one!” I said, my breath tripping over my words as it raced into my throat.

  “The second ring will be much harder to find. The one Neptune ripped from Aurora’s finger. He swore it could only be found when it was seen under the light of a full moon. But there was a catch.”

  “A catch?”

  “The ring was buried so deep it has never seen the moon’s light. And so it has never been found. Neptune and Aurora married under a full moon on the spring equinox, at midnight. At that moment, the sea’s tide is the lowest it ever gets — and only then is it low enough for the ring to be visible. But those conditions occur only every five hundred years. It’s virtually impossible to find it. We’ll never stop the curse.”

  “What curse?” I asked again.

  Aaron walked to a small recess. His breath misted the windowpane as he looked out. “After Aurora die
d, Neptune turned to hatred and anger. There were storms for years. Ships were wrecked at sea. Many fishermen died, many humans perished in the seas, over the years that followed. But even that wasn’t enough for Neptune. Even that couldn’t take away his rage.”

  “So what did he do?”

  “First he banned any more marriages between humans and merfolk. He swore the two worlds would never again live in harmony.”

  Well, yes, I knew all about that. “And second?” I asked.

  “Neptune and Aurora had two children,” said Aaron. “A son and a daughter.”

  “What happened to them?”

  “In his grief and sorrow, Neptune cursed them,” he went on. “His own children. Each of his own children, and their children, and every generation that followed — every single one of them would die young, and always on Aurora’s birthday, as she did. He couldn’t forgive her — and because of this, her family would forever be punished.”

  “His family too,” I said.

  Aaron nodded. “Their family. And there was another curse placed on them. They would never fit in, never be of one world or the other. They would be not quite human, not quite merperson. Whichever form they took, it would always be held back by remnants of their other form. Every single generation forever would be the same. Do you understand?”

  Did I understand? If only he knew how well I understood! It was almost the same as the curse on me! “Aaron. Look!” I thrust my hands in front of his face, opening my fingers so he could see how they were webbed.

  “Of course,” he said. “I should have noticed before. I was too busy looking at the ring. “You’re the same.”

  I nodded.

  “The only way to undo these curses would be to bring the rings together again,” said Aaron.

  “Because the curses came from hatred and anger,” I said, finally understanding the significance of what I had found. We just had to find the other ring, and we could end the curse on his family! And end the curse on me too! I could keep being a semi-mer! I wouldn’t have to lose my parents! The thought sent my hopes soaring. Till Aaron spoke again.

  “But that will almost certainly never happen,” he said. “The chance will come only once every five hundred years.”

  “When was the marriage?”

  “No one knows for sure. The wedding was shrouded in secrecy, protected by Neptune’s magic. No one has ever known the exact year it took place. I think it must have been about five hundred years ago, though. It could be more. The moment has probably already passed. So the curses will remain forever, and nothing will ever bring back harmony between land and sea.”

  Aaron fell back into silence. His words spun around and around in my head. I’d found one ring. Why couldn’t we find the other?

  “Where was it buried?” I asked suddenly. “The second ring. Where was it buried?”

  “Right where she died. Just beyond her home.” Aaron ran a hand through his sleek hair.

  “Her home?” I asked. I was pretty sure what he was going to say. Pretty sure he wasn’t just telling me any old story, someone else’s story. I was pretty sure it was his story. That her home was his home, her family his. That was when I realized I was pretty sure of something else too. The reason I felt so comfortable with him and cared so much about what he had to say — it was because he was like me. Caught between two worlds. It was almost as though I’d found a brother.

  “Yes,” he said. “She lived here at Half Light Castle. In fact, Neptune had the castle built especially for her, for them. A place of magic and beauty and love, where their two worlds came together. And ever since, it’s been a symbol of the exact opposite, keeping every generation separate from the rest of the world.”

  “Completely separate? Don’t you ever see anyone else?”

  “There has been more life here at different points in the castle’s history. But it’s never been a happy place since that time. And, with the curses, the family’s dwindled more and more over the years. It’s just me and Mother now. We have a few visitors who bring us our supplies, but they hardly talk to us.”

  “Why not?”

  “Mostly they’re sirens, employed by Neptune. They don’t dare go against Neptune’s rule. They’re all instructed not to talk to us, although there are a few who I’m secretly friends with,” Aaron said. “It’s a pretty lonely life,” he added.

  Sirens! That’s what he was going to say earlier, when he changed it to servants. I knew it! And I was right about Aaron being descended from Neptune and Aurora too! Before I had a chance to say anything, the alarm sounded again, crashing into every bit of space around us, filling my head with noise.

  Aaron jumped as though he’d been stung. “Mother,” he said. “I forgot!”

  “What is it?” I called over the din.

  “It’s my mother. She’s confined to bed. She rings it when she needs me. I didn’t go to her earlier. Emily, I have to leave.” Aaron hurried to the door. “I don’t dare take you with me; the shock will only make her worse.”

  Outside the chapel, waves crashed against the rocks. The sky was starting to grow light; above the mist, clouds were turning pink, anticipating the day ahead. Cobwebs shone brightly in the door frame: elaborate spiraling mazes in one corner, half-finished scraps and threads dangling loosely in another, gaping and half-empty like derelict houses.

  “Quick. Go back to the tunnels. It’s the only way. It’s too dangerous on the rocks.” Aaron led me to the door that would take me back to the cellar. “Down there,” he said, opening the door and virtually shoving me inside. “You’ll find your way back?”

  “Yes, of course.”

  “Come back soon!” he said urgently. “Promise me!”

  “I promise,” I said.

  “Good.” He allowed himself a brief smile. “I have to go now.” And with that, he closed the door and left me in the darkness.

  Lowering myself down, I made my way smoothly back to the cellar and set off for Fortuna. Heading back didn’t feel half so difficult. The current drew me along. The ring vibrated in my hand, buzzing warmly. It seemed as excited as I was. It was willing me to get back to Shona and tell her everything.

  As I swam, I watched the sky changing moment by moment, the clouds growing orange and bright. The sun rose in front of me, shining hard into my eyes as though it were a weapon sent to blind me. Beneath it, the mist rolled along the top of the sea like a thin layer of snow. Don’t let Millie be up yet, I said to myself, swimming as hard as I could to get back despite my tail feeling as though it were made of iron and despite my breath coming out in rasps, shorter and shorter with every stroke.

  The second I swam through the porthole, Shona was there.

  “Where have you been?” she whispered fiercely.

  “Is Millie up?”

  “No.” She shook her head. “I couldn’t sleep and I was calling you. I figured you must have still been asleep.”

  “Shona. I got there,” I said. “I got to the castle!”

  Shona whistled. “Flipping fins! How? What’s it like? Did you go inside? Does anyone live there?”

  I laughed, holding up my hands to ward off any more questions. “I’ll tell you everything,” I said. “Just let me get my breath back.”

  Shona listened in silence to the whole story. When I’d finished, she simply stared at me.

  “What?” I asked.

  “Emily, you have to find the other ring. It’s your only hope!”

  “I know — but I can’t. It’s impossible. No one’s seen it for hundreds of years. It’s buried too deep. It’s not suddenly going to turn up now!”

  Shona bowed her head. “We have to find it, Emily. We have to find a way. We can’t give up. There’s too much to lose.”

  “You’re telling me!” Shona wasn’t even the one with something to lose. I was going to lose the whole of the mermaid world or the whole of my life as I’d known it up until now. Mr. Beeston’s words hadn’t left my mind for a second. Neptune’s word is law. I would see m
y parents on the night of the full moon, one of them for the last time ever. And I didn’t even know which one.

  “And before you say I have nothing to lose,” Shona said, reading my mind as usual, “I do. I’ve got you to lose. And I’m not prepared to let that happen. OK?”

  I let myself smile at my best friend. “OK,” I said.

  We stared out at the castle. It seemed to be staring back at us, the mist curling around its base like a dark blanket, the turrets bright and harsh in the sun, the windows shining like lights.

  “We can find it,” Shona insisted quietly as she swam toward me and grabbed my hand. “Emily, you can end the curse! You just need to bring the rings back together. You’ll change Aaron’s life as well!”

  The thought made my heart soar. A day ago, I didn’t even know he existed; now my fate was inextricably linked to his. “Maybe it’ll bring harmony back to sea and land too,” I said. Before I could stop myself, I added, “And then Neptune would change his mind, and Mom and Dad could go on being together!”

  Then I stopped. How could I be such a fool? My shoulders slumped and I sank lower in the water as I thought about what I was saying. What if Mom and Dad didn’t even want to be together? The way things had been lately, they would probably be happy with Neptune’s new law! And then there was, of course, the fact that the pearl ring was buried so deep it would never be seen.

  I was going to lose a parent. It would happen just as Mr. Beeston had told us. When the full moon came, Neptune would bring my parents to me and I would say good-bye to one of them — forever. The thought was so dark and so huge, it felt as if I were falling into it, into the deep chasm that was my future. I stroked the gold band on my finger, pressed the diamond against my palm, looking for comfort, but it felt cold. It had no comfort to offer me.

  “Who am I kidding?” I said, my words as heavy as my heart. “We’re not going to find the ring. We’ll never stop all these terrible things from happening.”

  “We will NOT give up!” Shona said, swimming around in front of my face and lifting my chin just as Mom does when she forces me to listen. “Do you hear me?” she said sternly. “That is not my best friend talking. The one who explores shipwrecks and caves and breaks into prisons to rescue her dad! We’ll find a way. OK?”