“Did you swim to the island?” Harper asked, realizing that he must have.

“I think so.” He shook his head again. “I can’t really remember much. There was the song, then I was swimming, and then I was on the island. Those pretty girls were there, and … and Gemma. She kissed me…” He swallowed hard.

“Do you remember the creature?” Harper asked.

“The bird?” Alex asked, and she nodded. “Is that what it was? A really big bird?”

“It was more like a bird-monster,” Harper tried to explain. “But then it changed and turned into Penn.”

“So those pretty girls are some kind of shape-shifters?” Alex asked. “Because they turned into fish, right? Gemma and the girls turned into fish, then swam off?”

“Mermaids, I think,” Harper corrected him.

“This is so insane,” Alex said quietly, almost to himself, then he looked up at Harper, his dark brown eyes locking seriously on hers. “Stupid question time, but I have to ask. Gemma hasn’t, like … always been a mermaid, has she? This isn’t some family curse thing like on Teen Wolf?”

“No.” Harper smiled despite herself and shook her head. “No. There’s no history of mermaids or any other mythological beings in our family.”

“Okay. Good,” Alex said, then changed his mind and wagged his head back and forth. “Well, not really. If you knew what this was, it would be easier to deal with.”

“It certainly would,” she agreed.

“So you don’t have any idea what Gemma or Penn or the girls might be?” Alex asked.

“No,” Harper admitted regretfully.

“And you don’t know where they went?”

“Nope.”

“So. How are we gonna get her back?” Alex asked.

“Well…” Harper took a deep breath. “We figure out what they are and how to stop them, then we find them and we take Gemma back.”

TWO

Metamorphoses

Marcy had been talking for a while, but Harper hadn’t been listening. She sat at the desk, staring into space and trying to figure out what to do.

When Alex left the night before, they’d both agreed that they had to continue on with life like normal until they found Gemma. That meant going to work, even when Harper would rather be at home scouring the Internet for clues about what Gemma might have become.

She’d spent a lot of time on sites that claimed to be experts on Bigfoot and el chupacabra, but nobody had heard of a bizarre bird-monster that also turned into a fish-human hybrid and a beautiful teenage girl.

By the time she fell asleep very late last night, Harper had begun to believe that she’d made up the whole thing. It was some weird stress-induced hallucination. That was the only logical explanation for what she’d seen.

“But I was like, you can’t make a fur coat out of basset hounds,” Marcy was saying when Harper started tuning back in. “It’s not like I’m Cruella De Vil, you know?”

“No, it’s not,” Harper replied absently.

Marcy scoffed and stared at her above her dark-framed glasses. “You haven’t listened to a word I’ve said, have you, Harper?”

“You’re not Cruella De Vil.” Harper forced a thin smile at her.

Marcy rolled her eyes. “Lucky guess.”

“How is that lucky?” Harper asked.

The bell of the library’s front door rang as it swung open, and Harper pulled her eyes away from Marcy’s annoyed gaze to see Alex come striding over to the desk. He grinned broadly, which was a massive change from the grim expression he’d worn last night.

“You heard from her?” Harper blurted out, interrupting Marcy midsentence after she’d begun talking about basset hounds again.

“No.” Alex’s smile faltered for a moment as he rested his arms on the desk in front of her. “But I do have good news.”

“Yeah?” Harper leaned forward.

“I figured it out.” His smile returned as brightly as before. “Sirens.”

“Sirens?” Harper frowned in confusion. “Like police sirens?”

“Is this about Gemma?” Marcy asked, managing to sound concerned for once. “Did the police find her?”

“No,” Alex said. “Where’s your section on mythology?”

“Mythology?” Harper echoed, as he was already taking a step back from the desk.

“Yeah, like Greek mythology,” Alex elaborated.

“Back in the corner, past the children’s books,” Harper said, motioning to the other side of the library.

“Great.” He smiled wider, and before she could ask him anything more, he darted back to where she’d pointed.

“Alex,” Harper said as she stood up, but he just kept going, disappearing between the shelves of books. “Marcy, can you cover the front desk? I have to go see what he’s up to.”

“Uh, yeah, sure,” Marcy said, sounding just as confused as Harper felt. “If it’s about Gemma, take as much time as you need. But I have no idea what mythology has to do with her running away.”

“Yeah, me neither,” Harper muttered, then followed Alex to the back of the library.

She found him already leafing through a copy of Ovid’s Metamorphoses, in the middle of the mythology section. On her way after him, it had occurred to her what he meant by sirens, but the pieces didn’t completely fit.

“You think they’re sirens?” Harper asked skeptically.

“Yeah.” Alex nodded without looking up from the book.

“I don’t know, Alex. That doesn’t make sense.”

“Think about it.” He lifted his head to look at her. “The song? That’s what sirens are known for. Not to mention the whole mermaid thing.”

“Right,” Harper agreed. “But what about the bird-monster thing?”

“Still sirens.” He flipped a page in the book, scanning it frantically. A moment later, he smiled again and held the book out to her. “See for yourself.”

“What?” Harper asked, and Alex tapped a passage.

Aloud, she began to read, “Why should it be that they have feathers now and feet of birds, though still a girl’s fair face, the sweet-voiced sirens?”

“See?” Alex said almost gleefully.

“Maybe you don’t remember it, but Penn’s face was not that fair when she turned into the bird thing,” Harper pointed out.