And then I felt it! His hand touched mine. Just a flicker — just for a fraction of a second as our hands brushed past each other. Not long enough. The waterfall still raged.

  Come on — I can’t fight it much longer.

  I was slipping down. We didn’t have long. Aaron’s hand brushed mine again. This time, I grabbed hold of it as though my life depended on it. Maybe it did.

  His hand was warm against mine. He held on just as tightly — but nothing was happening. Please stop, I said silently to the waterfall. Please calm down.

  And then, exhausted and empty, I closed my eyes. I’d run out of energy. My hand slipped from the wall, my tail flapped lifelessly. It was all over.

  When I opened my eyes again, Aaron was in front of me, grinning widely. I was dreaming. I must have blacked out. Well, it was a nice dream. I hoped no one was going to wake me up any time soon.

  “We did it!” he said, untying the seaweed from around his waist.

  “Huh? You mean I’m awake?”

  Aaron let go of the seaweed. It floated slowly downward, swaying gently as it fell. “Look around you,” he said.

  That was when I realized there was no ground underneath me. We were floating freely — inside the well!

  “We did it!” I said.

  Aaron laughed. “I’m sure someone around here has already pointed that out!” He took my hand and started swimming upward. “Come on, let’s get out of here.”

  I snatched my hand away. “We can’t. Not without Shona.”

  “She’s down here, too?”

  I nodded. “I’m not leaving her.”

  “No. Of course you’re not,” Aaron replied. He flipped over and swam downward. “Come on, then. What are we waiting for?”

  We swam down to the bottom of the well — and then I remembered. “Aaron, we can’t get out. They put something in front of the door.”

  Aaron swam over to the rock. Grunting and grimacing, he pushed hard against it. The rock tilted slightly. “We can do it between us,” he said. “Push it with me. If we work together, we can get it out.”

  I joined Aaron, and we pushed and heaved and propelled ourselves forward with our tails. Eventually, the rock budged. Only a bit, but enough for us both to slither through, one behind the other.

  I led the way through the opening. “Come on,” I said. “Let’s go find Shona.”

  We swam down a tunnel that sloped lower and lower as it grew narrower and narrower, twisting and turning all the way. Its ceiling was jagged and gray, its sides pockmarked with tiny holes.

  The tunnel led us to a tall archway. We swam through it into an opening and looked around. Empty. High up, a row of knobbly rocks were squeezed tightly together like a village on a hill. Above us, the stone looked like sheets of paper, folded and rolled and hung from the ceiling. A pillar over to the left was like a giant finger pointing upward.

  Aaron swam to a deep recess, high on one side. “Emily, look!”

  I swam up to join him. It was another tunnel.

  “Come on, let’s try it,” I said.

  We swam into the tunnel, and, after a moment in the pitch darkness, we were out the other side. I rubbed my eyes. “We’ve found it!” I said. The opening where I’d last seen Shona.

  “Now all we have to do is work out where they’ve taken her,” Aaron said.

  We swam along the snaking pathways that led all around the inside of the caves, peering into each cavern we passed and calling out her name as loud as we dared. She was nowhere. The whole place felt deserted.

  “Look at that,” Aaron said as we passed a flat ledge with a tall, thin column stretching upward, like a tower that someone in a fairy tale would be locked away in and forgotten forever.

  I shuddered and swam on.

  “Wait! Look!”

  Aaron swam back to join me. It was one of the caverns — but it had a door. A real one, not just a curtain of rocks like the others. It looked as if it was made from a ship’s timber — and it had a rusty bolt across it.

  I grabbed the bolt. “It’s stiff,” I said. “Help me.”

  Between us, we worked at the bolt, pulling and levering it gradually along — until finally it came loose. I pushed the door and swam in.

  My eyes took a moment to grow accustomed to the darkness. Once they did, I saw something huddled in the far corner. I swam straight over.

  She was curled up with her head in her arms, shoulders hunched, tail flat and lifeless.

  “Shona!” I cried.

  She turned her tearstained face up toward me. “Emily,” she said, instantly getting up and brushing her tail down. “You found me!”

  We fell into a hug. “Of course I found you,” I said. “What was I going to do? Abandon you?” I pulled her over to the door. “Come on.”

  That was when she noticed Aaron. “Aaron! How did you —?”

  “We’ll explain everything later,” Aaron said. “Let’s get out of here first.”

  Shona stopped. “Wait — I need to say something first.”

  I sighed. “Please, Shona. I know you think these sirens are the whale’s whiskers but I’m telling you, they’re not. You have to believe me. They —”

  “Emily, stop,” she said firmly. “I don’t think anything of the sort. That’s what I wanted to say.” She lowered her head. “I was a silly shark-head,” she said quietly. “I should have listened to you. I should have trusted you. You’ve never let me down, and you never would. I’m sorry.”

  “What happened?” I asked. “How did you end up in here?”

  Shona’s eyes filled with tears, glistening in the darkness. “They made me sing,” she said. “But they said it wasn’t good enough.”

  “That’s what they said to me,” I said. “In my case, they were right, though.” I laughed and Shona half smiled. “But you’re a brilliant singer. They don’t know what they’re talking about!”

  Shona wiped the back of her hand across her eyes. “They told me their story.”

  Aaron swam across the room and hovered beside me. “What story?” he asked.

  “How they got down here. They said they’d been trapped here for years and years. They’d been friends all their lives. One of them — Melody — had been the best singer anyone had ever heard.”

  “She’s the one Miss Merlin told you about?” I asked.

  Shona nodded. “But then something happened. She went away for a long time, and when she came back, she couldn’t sing. When she tried, terrible sounds came out. Melody said she had to leave her home immediately. They didn’t know why, but because they were all such good friends, they said they’d come with her.”

  “And they came here?” Aaron asked.

  “Yes. She said they’d only need to stay a little while. But then all the other sirens lost their singing voices too. And the waterfall is the only way into the place, and it’s impossible to get back out.”

  I wanted to tell Shona that she was wrong — we were going to get out any minute now! But I wanted to hear the rest of the story first.

  “Melody told them the only thing that could break the waterfall was the beautiful sound of a siren’s song. She said if they could get their voices back, they would be able to get out.”

  Suddenly it all fit. “So that’s why they were so desperate for us to sing,” I said.

  “They all looked so happy when I started to sing. But then one of them went out to watch the waterfall.” Shona looked down. “She saw you there, huddled on the floor. She told the others . . .” Her voice trailed off.

  “She told them what?”

  “She said you looked really scared and miserable. They all had a good laugh.”

  I was just glad she hadn’t come at the point where we’d made it stop! Let them poke fun at me if they wanted to. We were going to have the last laugh.

  “When she came back and said nothing had happened to the water, they changed completely. They turned on me, hissed in my face, said my singing was — was —” Shona broke off.
r />   I swam toward her. “What did they say?” I asked softly.

  Shona turned her big, sad eyes up toward me. “They said my singing wasn’t beautiful enough. They said it couldn’t be, or it would have worked.”

  “And then they threw you in here?” Aaron said.

  Shona nodded.

  I took hold of her hand. “It’s OK,” I said. “I think your singing’s beautiful, no matter what a bunch of silly old sirens say. And more to the point, so does your singing teacher!”

  Shona sniffed. “But they’re real sirens! They’d know best, wouldn’t they?”

  I put a finger under Shona’s chin and lifted her face, just like Mom does with me when she wants to make sure I’m listening. “Their opinion doesn’t matter at all. They don’t know what they’re talking about. They’re bitter, twisted, nasty sirens who can’t sing anymore themselves and wouldn’t recognize a beautiful siren song if it swam right up to them and kicked them in the gills! Right?”

  Shona managed a half smile. “Right,” she said unenthusiastically.

  “And anyway,” I went on, “guess what? We’re getting out of here!”

  “But we can’t! The sirens said the singing would be the only way to get out.”

  “Well, that’s even more proof that they don’t know what they’re talking about, because we’ve found a way to stop the waterfall!” I swam back toward the door.

  “Really? How?”

  I stuck my head through the door to check that the coast was clear. “Well, we have!” I said. “We’ll tell you everything on the way.” I swam back out onto the dark ledge and beckoned to the others to follow. “Come on,” I said. “Let’s get out of this place!”

  “Try again,” I called down. “There must be something wrong.”

  Aaron and I were halfway up the well, but Shona was still right down at the bottom, splashing around uselessly on the seafloor.

  “I can’t,” she called up. “It’s still too powerful.”

  “Wait. I’ll help you.”

  Aaron and I swam back down and took Shona’s hand. Swimming back up into the well again, I tried to pull her up, but it was no use. I could swim through the water with Aaron, but I couldn’t pull her with us.

  “It’s as though the waterfall is still there, beating me down. I can’t swim through it,” Shona said.

  Our magic must only work on Aaron and me, I thought. It wasn’t strong enough to work for Shona, too.

  Shona’s mouth tightened into a small line. “You go,” she said quickly.

  “What?”

  “Look, it’s obvious what’s happened. You and Aaron can get through it. You have the power to do that — but it’ll only work for you two.”

  “Shona’s right,” Aaron said. “That must be what’s happening. It’s not strong enough for all three of us.”

  I looked at both of them. My two best friends. Or my best friend and — well, I still didn’t know exactly what Aaron was. And I didn’t know why the waterfall would stop only for us. We clearly didn’t have as much control over our power as we’d thought. Well, that made sense. Where Neptune’s concerned, nothing’s ever straightforward or easy. But I couldn’t help feeling that we were missing something — there had to be some way it could work, if only we knew how.

  One thing I did know, though, was that the three of us were in this together.

  “We’re not leaving you,” I said to Shona.

  “You don’t have a choice.”

  “Yes, we have,” Aaron said. “Do you think we could just go off and happily escape while you’re trapped here?”

  “But —”

  “But nothing,” I said. “Whatever we do, we’ll do it together. No one’s going anywhere till we’ve figured out how to get us all out. Deal?”

  Aaron and Shona looked at each other and then both turned to me. “Deal,” they said in unison.

  “Good!” I paused. “Now all we need is a plan.”

  We sat in silence, each thinking our own thoughts. Mine weren’t very helpful, so I decided not to bother saying them out loud. I guessed the others felt the same way.

  I watched a lone fish with a spiky back slither along in front of me, pecking at the seabed every few seconds, then moving on. It seemed so purposeful. It knew where it was going and how to get there. Would we ever be able to say that about ourselves again?

  A swishing noise outside the well broke into my thoughts. A second later, the seaweed curtain lifted. Someone was coming in!

  All three of us jumped up and swam to the farthest wall. As we pressed ourselves against the rock, I prayed that we could somehow become invisible against the dark shadows of the well.

  A moment later, a face appeared, and one of the sirens swam inside.

  She looked around the well and spotted us immediately. Pulling her hair away from her face and swimming over to us, she smiled. “Found you!” she said.

  I peeled myself away from the rocks and swam into the center of the well. “Don’t try anything. There are three of us and only one of you,” I said, trying to make my voice sound big and brave. Easier said than done when you’re scared finless and everyone knows it.

  The siren swam closer toward me. Instinctively, I backed away.

  “I’m not going to hurt you,” she said softly. That was when I recognized her. It was the one who had been kind earlier. Morvena.

  Aaron swam over to join me. Puffing his chest out and sticking out his chin, he swished his tail hard to make himself taller. He wasn’t going to let himself be thrown by seeing one of these sirens for the first time. Or if he was, he certainly wasn’t showing it. “Why should we believe you?” he asked. “Why should we even listen to you?”

  Morvena looked Aaron in the eye. “I can’t make you listen, and I can’t make you believe me, either. But I hope you will do both.”

  “Why?” Shona asked. She was still huddled against the rocks on the other side of the well.

  Morvena swam over to her and Shona flinched. The siren answered softly. “Because I think we can help each other.”

  “Why would we want to help you?” Aaron asked.

  I touched his arm. “Wait — let’s hear what she has to say. I think she’s different from the rest.”

  Morvena bowed her head slightly. “Thank you,” she said. Then she indicated above us. “I saw what you did up there just now,” she said. “I was following you — I wanted to make sure you were safe.”

  “Why would you care?” Shona asked. She obviously wasn’t ready to believe that any of the sirens could have good intentions toward us.

  “I know what the others are like,” Morvena said. “Some of them, anyway. You’re children. You’re not the enemy — and I’m not a monster.”

  “So what did you see?” Aaron asked, his tail flicking nervously.

  “I saw you do the impossible,” she said, her eyes shining and wide. “I saw you swim into the well.” She turned to me. “Why didn’t you leave?”

  “We couldn’t,” I said. “Shona couldn’t do it. Only Aaron and I can swim through it.”

  “How did you do it?” Morvena asked.

  Before I could reply, Aaron elbowed me. “We’re not telling you all our secrets yet,” he said. “You need to give us something first. Give us a reason to trust you.”

  Morvena let out a sigh. It sounded as if it contained a hundred years of sadness and regret.

  “We can’t get out of here,” she said.

  “I know — because you had your beautiful voices taken away,” Shona said from the corner. She still hadn’t moved.

  Morvena shook her head. “That isn’t the full story,” she said. “In fact, I’m certain that the singing doesn’t have anything to do with our being trapped here. I had suspected it for a long time, but today confirmed it for me.”

  “What do you mean?” I asked. “I thought you told Shona all about it earlier.”

  “We did — or at least the others did. I kept quiet, as I often do if I have nothing helpful to sa
y.” She turned again to Shona. Tilting her head, she spoke gently to her. “Your singing was the most beautiful thing these caves have heard for many years. It could probably have rivaled Melody’s own voice when she was your age.”

  Shona’s face flushed in an instant. “But the others,” she said. “They told me it was terrible. They said my singing was useless!”

  “That’s because they thought the sound of a beautiful siren song would open our prison and let us out. Then when you sang, nothing happened, and they were angry. But, you see, I wasn’t, because I know better than they do.”

  Aaron swam forward. “What do you know? Why would you know more than they do?” he asked, folding his arms. “And why should we believe you, anyway?”

  Morvena drew a breath. “Listen,” she said. “I’ll make a deal with you. I’ll tell you everything I know if you promise to try and help.”

  Shona and I looked at each other. She gave me a tiny nod. I glanced at Aaron, and he did the same. “OK,” I said to Morvena. “We promise.”

  “Well,” Morvena began, “many years ago — so long ago, now, it’s like a different lifetime — Melody came to me. I was her best friend. I still am.” Morvena paused. “I’m her only friend now.”

  “Why?” Shona asked. “What about the others?”

  “They blame her for everything that’s happened here. And in a way they’re right. But what’s the use of blame? It won’t get us out of here. All it will do is make our lives even more unpleasant than they already are.”

  “You were her best friend . . .” Shona prompted.

  “Yes. We told each other everything — or at least I thought we did. Until the day she disappeared.”

  “She disappeared?” I said. “What happened to her?”

  “That I’ve never known. She was gone almost a year. Then one day, she turned up, completely out of the blue, and in such distress that at first I thought she was dying.”

  “What happened then?” Aaron asked.

  “She said that something bad had happened. Something so bad that she was terrified. She decided that she had no option but to go into hiding, although she was sure it would only be for a while. Then she asked three things of me. One, that I never ask her what she’d done; two, that I never tell the others about the state she was in; and three, that I would never desert her.”