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.