"We couldn't take the risk of bringing their memories back." Mr. Beeston actually had the grace to look ashamed. His head hung low; his arms dangled limply by his sides. "I'm sorry, Emily," he said. "Things are different now. I would never, ever do anything ever again to hurt you or any of your family. You do believe me, don't you?"

I didn't reply.

Mr. Beeston reached out an awkward hand. He pulled at my sleeve. "Emily, I know I have wronged you, and for this I am in your debt," he said in his usual dramatic way. "To prove my sincerity, I'm telling you now, whatever you need, if I can ever help you with it, I will do it. I owe you one."

I nearly laughed. "You owe us one? What you owe us could never be repaid, even if you spent the rest of your life trying!"

He nodded. "I know. I'm sorry. I owe you more than I can express with mere words. But remember, things are different now. We have a shared mission - and I intend to do everything in my power to make it work."

I found myself softening a tiny bit. Could people change? Was it possible? Neptune had changed his mind - and his laws - on a lot of things lately. Maybe Mr. Beeston could change, too. I knew I would never trust him again, but what he said about doing anything for us - well, perhaps one day that promise would come in handy.

"And if it's of any interest to you, this incident has made me come to a decision."

"What about?"

Mr. Beeston paused for a long time. When he spoke, his voice had a catch in it, as though his words were climbing over a gravelly hill to get out of his mouth. "My mother," he said.

"Your mother? What about her?"

Mr. Beeston had hardly ever mentioned any family. The only time I'd ever heard him talk about his parents was when he'd come after me in the motorboat when I'd gone out to the Great Mermer Reef to rescue Dad. I tried to recall what he'd told me then. Something about his dad being happy to have a siren for a girlfriend, but then disappearing the minute he was born.

"Our conversation the other day got me thinking. I'm going to visit her," he said. "You see, your mother and I have something in common," he went on. "I, too, am estranged from my parents."

"Your dad left you as a baby, didn't he?" I asked as gently as I could. I know it was only Mr. Beeston, but even so, it wasn't exactly the kind of thing you threw in someone's face without a care.

He nodded. "Off without a backward glance," he said bitterly.

"So your mother brought you up?"

"Ha! That's one way of putting it!"

"What do you mean?"

"My mother - well, she was beautiful. She was a good siren. But more remote than the farthest horizon. Or, to put it kindly, let's say that when Mother Nature was handing out the mothering skills, mine was at the back of the line, if you get my drift. I was left to fend for myself from a very young age. Leaving home was almost an irrelevance - to both of us. In our hearts, we'd left each other many years earlier."

I thought of my own childhood up until last year. Growing up without my dad hadn't been easy. But I'd never for a second doubted Mom's love for me. I couldn't imagine what it would have been like without that. For the first time ever, I really, truly felt sorry for Mr. Beeston.

"Why do you want to see her now, then?" I asked.

Mr. Beeston shook himself. He cleared his throat and seemed to drag himself back into the present. "I take my work seriously. You know that."

I probably knew it better than anyone on the planet!

"We have been charged with the mission of making peace. Just like your mother, if I cannot make amends with my own kin, how can I be expected to succeed in the wider world? The answer is that I can't, and I wouldn't expect anyone to take me seriously if I tried. A job like this begins with family. I've decided. I'm going to see my mother - and I'm going to do it today!"

I was starting to feel an inkling of forgiveness for him, but something was still bothering me. "Hold on," I said. "The thing about my grandparents - it still doesn't add up."

"What doesn't?"

"Well, you said they were memory drugged."

"As indeed they were."

"In that case, how come they remembered, earlier?"

"They what? What on earth are you talking about, child?"

I explained about Millie bringing my grandparents to Brightport and everything that had happened.

"The silly woman," he snarled, back to his old self. "She shouldn't go messing around in things she doesn't understand."

"She was trying to help my mom! You know, the one who you've just sworn undying loyalty to."

"Hmph," he said, sniffing and straightening his jacket.

"So how come they remembered and then forgot again?" I asked. "Did you have anything to do with it?"

He shook his head. "I can't undo the memory drug now. Only Neptune can do that."

Neptune? I didn't fancy trying to get him to help. Most of my dealings with Neptune had involved catastrophe of one sort or another. "Well, someone else must be able to do it because it's just happened! Look, two minutes ago, you told me you'd do anything to help us, and now I'm asking you. How do we undo it?"

Mr. Beeston's face turned pink at the edges. "I'm telling you, child, it's impossible. Haven't you ever heard Neptune's saying on the matter?"

I shook my head.

"*Only the hand that is mightier than my own / May undo the magic from my throne,'" he quoted. "And as we all know, there is no one mightier than Neptune."

"So it can't be done?"

"Afraid not."

"But what about when they remembered for a bit - or seemed to?"

He shook his head. "It must have been a temporary blip. It happens sometimes, especially as they had only just returned to a place with mermaids nearby." Mr. Beeston shuffled uncomfortably. "Now if you'll excuse me," he said, "I do have some rather important work to do."

I left him to his important work and wandered away from the lighthouse in a daze, my head still full of questions. In particular, how were we ever going to fix this? Not just the situation with my grandparents, but the whole thing. We'd been told - ordered - by Neptune to make humans and merpeople get along better, and we couldn't even get our families to talk to each other.

What would Neptune do if he found out how badly we were failing?

I had plenty of experience with what Neptune does when he isn't happy, the kind of punishments he can dole out. And I knew one thing. I didn't want to be on the receiving end of another one. No, we had to sort it out. We simply had to.

All we had to do was figure out how.

I sloped over to Aaron's, too mixed up and miserable to try to work out any more answers on my own.

"Come on. Let's go out," he said. His mom had discovered a whole channel of game shows, and it was hard to talk over the TV.

"I thought maybe we could try to talk to my grandparents one more time," I said as we walked down the beach. We both knew it wasn't likely to do any good, but Aaron agreed that it would be worth trying one more time . . . just in case they remembered. So, we headed toward the row of cottages where they were staying.

"h.e.l.lo?" I shouted through the mail slot.

Aaron rapped on the door for the third time. Nothing.

"Where are they?" I asked.

"Maybe they've gone out?"

"Try one more time," I said.

Aaron lifted his fist to knock again, but stopped midair. "Hang on," he said. "Look." He pushed the door and it swung open. "Should we . . . ?"

I peeked inside. "Nan?" I called. "Granddad?" There was no reply. I turned back to Aaron. "Come on."

We went in. Creeping around, feeling like burglars, we looked in every room. Not that it took long. There are only four rooms in these cottages - and every one was empty.

"They've left," I said, plonking myself down on one of the armchairs.

"All their stuff's gone."

"And they were in such a hurry to get away from us that they didn't even lock the door behind them when they left!"

Aaron reached out and pulled me up from the armchair. "Come on," he said. "Let's go."

We walked along the beach, heading back to the pier, both lost in our thoughts. I hoped his weren't quite as miserable as mine. In other words, I hoped he wasn't thinking about the fact that every single thing I ever tried to do to make things better only seemed to make them worse. And I hoped he wasn't thinking too hard about how much trouble we were going to be in with Neptune if we didn't hurry up and get some peace talk going on around here.

"Oh, great," Aaron said heavily.

I looked up to see a familiar figure heading toward us. Mandy Rushton. That was all we needed.

She stopped right in front of us, hands on hips. For a second, a strange look flashed across her face. Her expression was baffled and contorted, as though it were being pulled in two directions at the same time. Have you ever seen a film or cartoon where someone's trying to decide between good and evil and they have a little angel sitting on one shoulder and a devil on the other, both talking to them at the same time? There was something about Mandy's expression that reminded me of that.

And then I guess she must have listened to the devil, because she looked me right in the eyes and smirked. "Oh, look," she said. "Someone's left a pile of trash lying around on the beach again." Then she turned her scowl on Aaron. "In fact, two piles of trash," she added.

So much for thinking Mandy Rushton might have an angel sitting on one shoulder!

"Excuse me," I said. I tried to get past her, but she stepped to the right so that she was still in my way.

"Got somewhere important to be, have you?" she sneered. "Oh, poor you, that nasty Mandy Rushton getting in your way? Well, it just so happens I've got somewhere important to be, too." She took another step closer toward me. Her face was inches from mine.

I wanted to ask her to stop it. I wanted to remind her we'd been friends once and ask her if we could do it again. I stopped myself, though. I wasn't going to go begging her. It would only give her more ammunition to throw back in my face. Mandy would never be friends with me again. The memory drug had made sure of that.

Aaron reached out and took my hand in his to rea.s.sure me.

Mandy burst out laughing. "Aw, how precious," she said. She stuck her bottom lip out and rolled a finger on it. "Poor widdle Emily, got to have her new boyfwiend hold her handy-wandy."

"He's not my -" I began. Or was he? How did you know if someone was your boyfriend or not? I'd never had one before, so I wasn't sure. Did you have to announce it to each other? Did one of you ask the other one, like a marriage proposal? Do you, Emily, take me, Aaron, to be your boyfriend? How did you know? And why did no one tell you these things?

Mandy was still laughing. "Ah, so sweet. Feel better now? So scared of Mandy-Wandy that you have to hold each other's hands. You're pathetic!" She stuck her face so close to me, her nose was almost touching mine.

And then I felt it. The tingling feeling in my arms. Like pins and needles, only - well, nicer. It felt a bit like having soft, fine sand trickled over my fingers, then up my arm. Soon, the feeling spread into my whole body. Something was happening.

Mandy took a step back.

I looked at Aaron. He could feel it, too. I could see it in his eyes.

Mandy opened her mouth to speak. She curled her face into a sneer. Or she tried to, but it stopped halfway so that her expression ended up half-sneering and half-perplexed. It reminded me of what Mom always used to say when I made faces. "Better watch out, sausage," she'd say. "If the wind changes, you'll be stuck like that."

Mandy's face seemed to be moving in slow motion now. I could almost see the cogs working in her brain, going back to Allpoints Island. Remembering. I think she's starting to remember! I gripped Aaron's hand even tighter.

"We're friends," she said finally, in a quiet voice that was so different from the voice she'd been using a moment ago, you would have sworn it was a different person.

I held my breath, keeping my mouth tightly closed, afraid to do anything in case she forgot again.

"We were friends," Mandy repeated. "We were on an island. You had a tail, and my dad wanted to put you in a show." Her voice was soft and dazed. She sounded as though she was talking from inside a dream. "There was a big ferry." She suddenly stopped and took another step back. Her eyes darkened. "There was a monster," she said slowly. "We saved lots of people, you and I, didn't we?"

Finally, she looked at me. She caught my eye and I nodded.

"It was nice, being friends," Mandy went on.

I smiled. "It was, yes."

None of us spoke for a while. Then Mandy took a breath and said, "Maybe we should do it again then. Shall we?"

She'd really remembered! I grinned at her. "Yes, please!"

She grinned back at me. I still didn't quite believe that it would last.

Mandy turned to face Aaron. "That means we're friends too, if you want to be," she said.

"Fine by me," Aaron said, gripping my hand a little bit closer. The tingling feeling went through me again.

"I'm sorry," Mandy said to us both. "Start again?" She held out a hand as a gesture of peace.

I took Mandy's hand and shook it. "Start again," I said. Then she and Aaron did the same.

None of us was quite sure what to do after that, and I kicked the sand around with my feet, trying to think of what to say next.

Aaron got us out of it. "Come on," he said. "Let's go to the theme park!" We still hadn't actually been inside yet, in case we ran into Mandy, but I knew he'd been dying to see it.

Mandy looked relieved. "Cool," she said. "I'll show you around."

We headed up the beach together. "And you can tell Mandy everything she's missed along the way," Aaron said.

I wasn't sure I was ready to trust her with everything just yet, but as we walked, I started to tell her about leaving the island, the journey back to Brightport. She told me what had been happening at Brightport High.

Nothing out of this world. Nothing top secret. Just enough to fill the s.p.a.ce between the beach and the rides, and to start closing up the gaps between us, too.

After Mandy showed us around the theme park, I needed some time to think about everything that had happened. My grandparents had remembered the past and then forgotten. Would it be the same with Mandy - or was there a way to undo the curse forever?