She explained the curse as best she could—about why Demeter had punished the girls, so now they were stuck together, shifting between mermaid form and bird-monster. She told Harper why she’d left, about what had happened at Bernie’s Island, how she didn’t know Bernie was dead then, but she knew she had to do whatever it took to protect Alex and Harper.

She told Harper about the way things had been at Sawyer’s house, and how she’d been so sick at first that her hair had been falling out. She even told her about the weird hunger lust she’d felt, and how she’d lost control for a moment and kissed Sawyer.

There were only two things she left out of the story. Gemma just couldn’t bring herself to tell Harper about feeding and that she’d killed someone. Nor could she tell her that the sirens needed to eat boys’ hearts to survive. And thankfully, Harper didn’t ask.

Gemma knew that Harper had to have suspicions. She’d seen the bodies, so Harper had to know the sirens killed boys and tore them open for a reason. But it must have been one of those things that Harper didn’t really want to know, the way sometimes parents suspect their kids are having sex but never ask. Sometimes not knowing is better.

The other thing Gemma couldn’t tell her was that she might die. Harper was hoping the sirens would wait as long as possible to find Gemma, but what she didn’t know was that they couldn’t wait too long. If they didn’t find her within a couple weeks, Gemma would be dead.

The reason Gemma didn’t tell Harper this wasn’t so much that she didn’t want to worry her, but that she didn’t want Harper to prevent it. Gemma didn’t want to die, but right now it was the only way she knew how to break the curse. It might be better if they didn’t find her: if she died, so would the sirens.

“I’m sorry,” Harper finally said. Her knees were pulled up to her chest, and she rested her chin on them.

“Why are you sorry?” Gemma asked, tilting her head to look at her sister.

“I’m sorry that you had to go through all this,” Harper said. “And you had to go through it alone. So much of this happened when you were at home, and you didn’t feel like you could tell me or Dad any of this.”

“Harper.” Gemma pushed herself up so she was sitting straighter. “You guys didn’t do anything wrong. I couldn’t tell you any of this because it’s insane.”