“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.

“Obviously this isn’t completely accurate,” Alex said, refusing to be deterred. “Some books say there are only two sirens, while others say there are as many as four. Some describe them as mermaids, others as birds. None of them get it completely right, but maybe that’s because they change form.”

Harper narrowed her eyes, thinking. “What do you mean?”

“Maybe Ovid saw them as a bird.” Alex pointed to the book in Harper’s hands. “But others saw them as mermaids. The girls can change their shape, like you saw. The only constant is their song. And we know they have that.”

Biting her lip, Harper stared down at the book in her hands. What Alex said made sense. Or it would have, if any of this made any sense.

“This is mythology, Alex,” Harper said, shaking her head, and she handed the book back to him. “None of this is real.”

He groaned. “Oh, come on, Harper. You saw the same things I did. This is real, and you know it.”

“Fine.” Harper crossed her arms over her chest. “Let’s say you’re right. What we saw … they were sirens. Is Gemma one of them? How did she become one?”

“I don’t know. So much of what I’ve read contradicts itself.” Alex motioned to the shelf of books beside him. “I was researching on the Internet all night, but I was hoping that maybe actual books could offer some clarity.”

“Well, how did the sirens become sirens in the first place?” Harper asked.

“From what I can tell, it had something to do with pissing off one of the gods.”

Alex turned away from Harper to focus his attention on the books. His fingers trailed along the spines as he scanned for a title.

“What are you looking for?” Harper asked, moving closer to him to help him look.

“I read a passage from a book online. I think it’s called … Argonautica or something.”

“Here.” Harper reached up past him, taking a worn copy from the top shelf.

She picked up an encyclopedia on Greek mythology, then started grabbing any book that might possibly have information on sirens, including one called Mythology for Dummies.

As she began gathering books, she handed them to Alex. Once he had a small stack, he sat down on the floor right between the two shelves and spread the books out around him.

“There are tables we can sit at,” Harper said. “There’s even an overstuffed couch.”

“Here’s good,” Alex said, already flipping through one of the books.

Shrugging, Harper sat down across from him and folded her legs underneath her.

“So.” She rested her arms on her knees and leaned forward. “Tell me what you already know.”

“I don’t know how much I ‘know’ per se, since there seems to be a lot of misinformation,” Alex said.

“You think they became sirens because they angered the gods?” Harper asked, and he nodded. “But Gemma didn’t anger any gods.” Then she changed her mind and shook her head. “At least, I don’t think she did.”

“I don’t think she did, either,” Alex agreed. “So maybe she isn’t one.”

Harper thought back to the end of the other night, when she’d seen Gemma disappear into the ocean in the pale pink light of early morning. Even then, her tail had been unmistakable. Gemma had definitely had a mermaid form.