“I can’t remember it all. Most of it didn’t make sense. But there were a couple of things he kept repeating over and over.”

  “What were they?”

  “He said he’d remembered something really important. More important than anything else he’d remembered up to now.”

  “Go on,” I said, half desperate to know what it was and half hoping she was going to spin around in a double backflip, splash me with her tail, and tell me the entire thing was a big joke and she’d come to take me home.

  What she actually said made my insides do a double backflip.

  “He said he’d remembered he had a brother. A twin, in fact.”

  “A what?” Neptune had a twin brother? And he’d forgotten? Had Shona heard correctly? Surely she must have made a mistake.

  “He said all he knew was that he had a long-forgotten twin, and that with the return of this memory came a new feeling of dread. Something terrible had happened. Something so terrible that it was still locked behind the doors of his deepest memory.”

  Before I could answer, a splashing sound behind me made me spin around.

  “Emily!” It was Aaron.

  “Where did you come from?” I asked.

  “I was looking for you when we docked. I saw you on the deck, and then I saw a couple walking toward you. I could tell you were thinking about jumping into the sea. And they were about to see you do it. I got the feeling that a couple of people setting off a “girl overboard” alarm might not have been part of your plans, so I quickly pointed out a mountain on the other side of the ship and stood chatting with them till I was pretty sure you’d had long enough to do whatever it was you were doing.”

  “And then you came down to find me and see what I was up to,” I said.

  “I came down to check you were all right,” Aaron corrected me.

  “Aww, you two,” Shona said. “Just as mushy as ever, eh?”

  “Hmm,” I said awkwardly.

  Aaron’s cheeks flushed. He turned to Shona. “Anyway — what are you doing here? What’s happened?”

  Shona caught Aaron up on everything she’d told me.

  “So then what?” Aaron asked. “What else did Neptune tell you?”

  “Not a lot,” Shona said. “He spent about five minutes barking down the phone before I had a chance to say anything. Then he suddenly stopped. I wondered if the connection had broken or something, but I couldn’t say anything . . .”

  “Because then he’d realize that it wasn’t either of us on the end of the shell phone,” I put in.

  “Exactly. He kept saying your names, asking if you could hear him. I was tempted to answer and pretend I was you, but I didn’t dare. I couldn’t risk getting you into trouble. But he was getting more and more worked up. I’ve never heard him like that. He kept repeating the thing about his twin brother, and how upset he was, and how bad it was for you. And something about the ice, and a glacier slowly melting, but I couldn’t tell what he was saying by then — it was all too garbled.”

  “What did you do?” Aaron asked.

  “I just held my breath and kept listening. Eventually, when no one was replying, he gave up and went. He said he’d keep trying to remember, and that you had to keep your shell phone nearby and wait for another update.”

  “Which we would never get because you had Emily’s phone,” Aaron said.

  “And you lost yours,” I reminded him sharply.

  Shona gave me a questioning look but let it go. “I guessed something like that must have happened,” she said. “I tried to call you but nobody answered. That was when I knew I had to come and see you.”

  “How did you find us?”

  Shona smiled. “Hanging around with you for the last year has helped me hone my detective skills!” she said. “Neptune said something about the Land of the Midnight Sun on the shell phone. I looked it up at the library. Once I knew where it was, I checked out departure dates of all the ships in the area and found the one that matched up with when you’d left. Then I memorized its itinerary so I knew where you’d be on which day — and here I am!”

  I stared at her. “You did all that for me?” I asked.

  “You’re my best friend. You’d do the same for me,” Shona said. Then she paused — and reddened. “Em, I’ve got something else to tell you. . . .”

  “What?”

  “I was in such a hurry to get to you that I left the shell phone at home. I’m so sorry.”

  “It doesn’t matter,” I reassured her. “We’ve gotten this far without them; we can manage to carry on without them, too.”

  We fell silent for a moment as we all tried to figure out exactly how to carry on, and what our next step should be. I thought over everything Shona had just told us. And then it hit me. I turned to Aaron. “The ice statue in the mountain!”

  “The one of Neptune?” Aaron said.

  I shook my head. “It wasn’t Neptune!”

  “It wasn’t Neptune? Of course it was Neptune. It was . . .” Aaron stopped. I could tell by the way his face drained of color that he had caught up with my thinking.

  “You’re right, it wasn’t,” he said. “The ice statue was Neptune’s twin brother.”

  We filled Shona in on everything we knew and all that had happened. It seemed a bit pointless to hold on to it being a secret now that she was actually here with us.

  “You have to go back there,” Shona said.

  “Back there?” I repeated, hoping I’d heard wrong. I couldn’t think of anything in the world I’d like to do less than go back inside that mountain.

  “Shona’s right,” Aaron said. “We have to go back to the statue. Neptune remembered that he’s got a twin brother, and he’s filled with feelings of dread.”

  “And he remembers something about ice,” Shona added.

  “Neptune’s brother is pretty much an ice sculpture, like everything else down there,” I said. “That must be why Neptune’s so upset. Someone turned his brother to ice — and then took his memory away.”

  “Exactly,” said Aaron. “And our mission is to undo what happened.”

  “So we have to bring Neptune’s brother back to life, and find out who did it — and who stole Neptune’s memory,” I said, wishing it weren’t true.

  “I wish it weren’t the case, either,” Aaron said, reading my mind as usual. I used to find it romantic; now it was just irritating. “But we have to do it. We finally know exactly what our mission is.”

  I nodded. “We need to take the other crystals — like the one that melted the sculptures — find Neptune’s brother again, and get a crystal to melt him.”

  I could hardly believe it, but I knew it was true. We really did have to go back to that place. The place where the frozen people were all coming to life and where the scary shark with the giant spear was on the search for us.

  I looked out to sea, trying to imagine going out there again. That was when I spotted the swell coming into the harbor. The water had been relatively calm since we’d gotten in here, but a small hill was rolling toward us now.

  “Aaron, Shona . . .” I said, holding out a shaky finger.

  They turned to look where I was pointing. Just as they did, the swell hit the outside of the harbor, crashing over the pier as if a bomb had exploded in the water. It was the biggest wave we’d seen yet.

  “It’s fine,” Shona said calmly. “We’re merfolk. We can handle the swells of the sea.”

  “Maybe out in the open ocean we can,” I said. “But I’m not so sure about a freak wave that seems to be heading directly for us — and is about to fling us against the harbor wall!”

  Shona looked again at the wave. She turned pale. “You’re right,” she said.

  The swell was rolling higher and higher, building into a peak, and starting to crumble in an avalanche of ferocious white froth.

  “We haven’t got time to get out of the port!” Aaron gasped.

  “Dive down as far as you can!” I yelled over the thundering sound of
the wave. “It’ll be gone in a second. If we get separated, meet at —”

  And then it came. The wave picked me up, like a giant tucking me under its arm. Briefly it lifted me, then, CRASH, hurled me under. It felt as though the weight of the entire sea was collapsing on top of me, holding me down, then spinning me around and around. Now I knew how it felt to be inside a washing machine on the spin cycle. And I didn’t like it.

  The world had turned white and silent, and upside down.

  I tried to relax and let the water do what it wanted to do. It was only water. It wouldn’t hurt me.

  Finally, the wave passed and I began to swim back to the surface. Only, I wasn’t sure which way the surface was. And before I’d gotten anywhere, the next wave was on me. Thundering over me, wrapping me into a ball, and hurling me around.

  Again, I tried to stay calm; again, I clawed my way toward the light. Again, I was beaten back down.

  Finally, after one last pummeling and a couple more dunkings, it was over. The swell had passed.

  Gasping and shaking, I looked around. The water was full of bubbles and foam; it looked like the fizziest drink in the world had been shaken up and poured all around me. A hundred tiny silver fish darted toward one another to reform as a shoal, then turned and swam off as one. A sleepy ray flicked its cape, as if to shrug off the swell, and smoothly slithered past. The seabed itself swirled like an underwater sandstorm.

  “Emily!” Shona was swimming toward me.

  “You OK?” I asked.

  “It’s Aaron,” she said. “Come, quick.”

  I followed her through the swirling water down to the seabed. Aaron was in the middle of some rocks. Literally.

  I swam over to him. He was lying on the seafloor, a huge boulder half on top of his tail, cuts all across his face and arms. “You’re bleeding! What happened?”

  Aaron nodded toward the boulder. “Came out of nowhere,” he said, gasping and wincing as he spoke. “The wave threw it at me.”

  I wanted to hug him and tell him I’d do anything I could to stop him from hurting, but I made myself hold back. Instead, I swam toward the boulder. “Shona, help me. Let’s see if we can move it.”

  We pushed and heaved at the boulder as Aaron gripped on to his tail and clenched his teeth against the pain.

  “Does it hurt really badly?” I asked.

  He just nodded and tightened his jaw.

  “Hold on. We’ll get it this time,” I said firmly. “Shona, wait till I say.” I felt for the movement of the swells. If we got the rhythm right, we could do it. “OK, one, two, three — push!”

  We heaved our weight against the boulder. Nothing. “And again,” I said as the swells rocked back toward us. “Push!” Again and again, we heaved and rocked until, finally, the boulder moved enough for Aaron to roll out from under it.

  He inched away from the rocks, pulling himself along with his hands. “I can’t use it,” he said. “My tail — it’s not working. I think it’s broken.”

  “Tails don’t break,” Shona said. “It’s just bruised.” She glanced at Aaron’s tail. It had turned black and purple where the boulder had been on it. “Badly bruised,” she added.

  Aaron tried to move again. “Aarrgh!” He clutched his tail.

  “Try just using the end of it,” I said, “where it’s not so bad.”

  Aaron flicked the tip of his tail. It lifted him a tiny bit in the water. “OK,” he said. “I can do that.” Grimacing and as white as ice, he inched along at the pace of a starfish.

  After about ten minutes, we finally got back to where the ship was moored. “I can’t do this,” Aaron confessed. “There’s no way I can go back to the mountain. I’ll just be a liability. You need to go without me. I’m so sorry.”

  “Aaron, it’s not your fault,” I said softly. Looking at his face creased up with pain and his lifeless, bruised tail dragging along behind him, I couldn’t hold on to any of the anger I’d been feeling.

  “Let’s get Aaron back on the ship, and then I’ll go to the mountain with you,” Shona said.

  I looked at her. “Are you sure?”

  “Of course I’m sure,” she said. “No discussion.”

  “OK,” I said

  Between us, we got Aaron to the shore and let him rest for a moment. “You need to go,” he said. “I’ll find Mr. Beeston. He’ll look after me. I’ll be fine. Go on, go. Let’s get this thing over with.”

  “OK.” I briefly touched his hand.

  Instantly, he closed his fingers around mine. “Be careful,” he said. “I don’t want anything to happen to you.”

  I felt as if I’d swallowed one of the rocks. It was jamming up my throat. I couldn’t speak. Instead, I quickly squeezed his hand before letting go. “Come on,” I said to Shona. “Let’s go.”

  Silently, we swam away from Aaron, away from the ship, away from the harbor and back to face the mountain, the ice, the spear-wielding shark — and whatever else might have come back to life and be lying in wait for our return.

  After swimming for what felt like hours, we eventually found our way to the mountain. The first stroke of luck we had was that the tide had come in, and the entrance Aaron and I had come out of earlier was underwater now — which meant that Shona could swim into it. I hoped this was a good omen, and that everything else would go our way. Hoped, but didn’t seriously believe.

  After a few twists and turns, and a couple of changes in direction, Shona stopped swimming. “Are you sure this is right?” she asked. “We don’t seem to be getting very far. In fact”— she looked around —“I think we might be swimming in circles.”

  “I think it should be down this way,” I said, trying to sound as if I knew what I was talking about, when in reality everything was looking unfamiliar now. It had been a dry cave the last time I’d been here, and now the whole thing was submerged — either from the tide, or from the melting ice, or both.

  We swam on. Soon, I noticed bits of ice floating past us. That was when I knew we were going the right way. We weren’t just swimming down a river created by the high tide anymore — we were swimming through what had been ice the last time we came, but had now melted and spilled out along various forks of the tunnel.

  “We’re nearly there,” I said. One more corner and we would be at the spot that Aaron and I had reached in the night.

  And then I heard voices coming our way.

  “Hide!” I shoved Shona into a crevice in the wall and squeezed in beside her.

  Two mermen were swimming toward us. Their faces were thin and hard. One had straggly, unkempt gray hair; the other was bald. Their tails were like long, sharp, glinting knives: one jet-black, the other a shiny, silvery gray. Both wore matching scowls.

  “Yes, of course, it’s obviously fantastic,” one of them said impatiently as they approached our hiding place, “but none of it matters without Njord.”

  The mermen were swimming right past us. I held my breath and prayed they wouldn’t see us.

  “I know,” the other one replied. Neither of them looked our way. “We need to find more crystals. One was never going to be enough for him.”

  “It would help if we knew where the first one had come from,” the first merman said, and I didn’t hear any more of their conversation, as they’d gone out of earshot.

  I let out a heavy breath. Clearly too heavy, as one of them turned around.

  “What was that?” he said. “Is someone there?”

  “Look! A couple of mermaids in the shadows!” the other one said.

  “What do we do?” Shona hissed.

  “Swim!”

  We flicked our tails as hard as we could, propelling ourselves along the channel, past fish with bright-blue bodies and startled looks on their faces and away from the scary-looking mermen.

  “Hey! Come back!” the mermen yelled. It took them about half a minute to catch up to us. One of them grabbed the end of my tail.

  “Who are you?” he demanded. I struggled to get away from him, b
ut he was too strong.

  The other one had a hold of Shona. “How did you get here?”

  “Let us go!” Shona squealed.

  “Let’s take them to the boss,” one of the mermen said.

  “Are you sure?” the other one replied. “There’s not a lot he can do while he’s frozen.”

  “He’s not frozen. He can move his mouth, his fingertips, and the tip of his tail; most importantly, he can speak. That’s all he needs to do. We follow the great Njord’s orders, not our own.”

  “What’s a ‘great Njord’?” I asked before I could stop myself. Maybe it was similar to a fjord. It sounded similar enough.

  “Who, not what!” the merman still gripping my tail with his hands snapped.

  “OK, who’s a Njord, then?”

  “Our leader.”

  The merman who had Shona nudged his head in the direction we’d been heading. “Come on,” he said. “Let’s go. They’ll find out soon enough.”

  Then he leaned down and grabbed a long strand of seaweed. Pulling it up and biting into it with his teeth, he quickly wrapped it a couple of times around the end of Shona’s tail. He passed it back to the other merman, who did the same to mine.

  “Just in case you had other plans,” he said, showing half a mouthful of yellow teeth as he laughed in my face. His breath nearly made me faint. It smelled like a bin full of dead fish that had been left to rot for a year.

  The mermen swam along the tunnel, pulling us behind them. “Not a bad catch for the first day back in business,” one of them said.

  “Instant promotion, I’m thinking,” the other one replied.

  Shona and I wriggled and writhed and grimaced as we half swam and half got dragged to the area in the middle of the mountain. I tried not to think too hard about what was waiting for us, and what this Njord guy was going to do with us once we got there.

  “Bring them closer. Let me see their faces!”

  The guards had brought us to the exact place we needed to be, to the exact person we had wanted to find: Neptune’s brother! I didn’t know whether to be terrified or relieved. Although, I have to say that after being dragged along and tied up with seaweed, to face an almost identical replica of Neptune — only mostly made out of ice and looking down at me with loathing and disgust on his face — I was tending toward the “terrified” option.