“That’s right.” Thea took a deep breath and brushed sand off her bare knee. “Aggie was actually my full sister, unlike Penn, who is only our half sister.”

“You had the same father as Penn but different mothers?” Gemma asked.

“Yes, but our mothers were actually sisters,” Thea said with a wry smile. “It was all very incestuous back then. The gods often moved around, sleeping with each other’s siblings and children.”

Gemma wrinkled her nose. “That’s gross.”

“So it is,” Thea agreed. “But that’s how things were done.”

“And you just went along with it?” Gemma asked.

Thea thought about that for a moment, then nodded. “I tried to.”

“But Penn didn’t,” Gemma said, turning her attention back out to the water, where Penn and Lexi were still taunting Sawyer.

“Penn’s never really been a go-with-the-flow kind of girl.” Thea laughed, but it was a hollow, bitter sound.

“What about Aggie?” Gemma asked, using the same pet name that Thea had used for her. “What was she like?”

Something dark passed over Thea’s face, and any trace of a smile fell away. She lowered her eyes, staring off at nothing.

“Aggie was kind,” Thea said. Her voice was naturally huskier than the other sirens’, but it became deeper now as she spoke, heavy with sadness. “Penn says that made her weak, and maybe it did. But compassion is still something that ought to be admired.”

“So what happened?” Gemma asked. “Did Aggie die because she was nice?”

Thea stared out at the ocean, and her expression went dark again. “Aggie thought we’d lived long enough. We’d had more than our share of time on this earth, and we’d experienced more and seen more and enjoyed more than maybe any other being here.

“But all of that came with a cost,” Thea went on. “And Aggie thought that we’d caused far more than our fair share of death. She said that we had enough blood on our hands, and it was time for us to go.”

“Go?” Gemma asked.

“Yes,” Thea said. “Aggie proposed we stop eating and go off into the sea to swim together until our bodies gave up and we died.”

“She wanted you all to die together?” Gemma asked.

“Yes. That was her grand idea.” Thea took a deep breath, and when she spoke again, her voice was totally flat and emotionless. “So Penn killed her.”

Gemma waited a beat, thinking she’d misheard her. “She…” Gemma shook her head. “She just killed her?”

“There was no other choice, we didn’t want to die.” Thea spoke quickly now, all her words running together in one long string, and they lacked any conviction. “And we couldn’t let Aggie kill us, so it was us or her, and it was going to be her either way. We had no other choice.”

“How did Penn kill her?” Gemma asked, realizing she might have a chance to learn about a siren weakness. But Thea only shook her head.

“Just because I’m talking to you doesn’t mean I’m stupid,” Thea said. “I’m not going to tell you how to kill a siren.”

“What happened after Aggie died?” Gemma pressed.

“The timing was the worst part of it,” Thea said. “The full moon was coming, and we didn’t have another siren planned. And when we finally found one, she died. Penn had her eye on you, but we thought you were too young. Things get more complicated when you get involved with underage girls. Their parents and family tend to pursue them more.”

“So what happened to the other girl?” Gemma asked.

“Girls, actually,” Thea corrected her. “There were two of them before you. We found them in nearby towns and tried them out the same way we did you.”

“What do you mean?” Gemma asked.

“You remember,” Thea explained, waving her hand vaguely. “We brought them out to the cove, wrapped them in the gold shawl, and they drank from the flask.”

She did remember that, but not very clearly. The night she turned had been a blur. She’d been swimming out in Anthemusa Bay back in Capri, and as soon as she’d heard Lexi singing, everything seemed to stretch and distort.

The only thing she could remember with real clarity was the awful taste of the liquid in the flask. It had been thick, and burned going down her throat. And then she’d passed out, and in the morning she’d woken up on the rocks with a gauzy gold shawl wrapped around her.

Later, Penn had explained to her what the liquid had been—the blood of a siren, the blood of a mortal, and the blood of the ocean. That had been the mixture that had actually turned her into a siren, but until now she hadn’t questioned the purpose of the shawl.

“What’s the significance of the gold shawl?” Gemma asked.

“It was Persephone’s,” Thea said. “She was supposed to wear it in her wedding.”

Persephone was the reason for them becoming sirens. Thea, Penn, Aggie, and their friend Ligeia were supposed to be watching Persephone, but instead they were off swimming, singing, and flirting with men. Persephone was kidnapped, and her goddess mother, Demeter, cursed them in punishment for not protecting her.

“What that has to do with the ritual, I don’t really know,” Thea admitted. “It was all part of Demeter’s instructions, and we have to follow them.”

“So then what happens?” Gemma asked. “You wrap the girls in the shawl, give them the potion, then what?”

“We toss them into the ocean,” Thea replied simply. “The mixture is supposed to turn them into a siren, and that will protect them. If it doesn’t take, then the girls drown.”

“And you’d already drowned two girls before me?” Gemma asked, her heart hammering in her chest. “And you just tossed me into the water and hoped for the best?”

“Essentially, yes,” Thea said. “You were our final hope. When you washed up on shore, alive, we were all so relieved.”

“I nearly died!” Gemma said, indignant.

“Yes, but you didn’t.” Thea gave her a hard look, signaling her to stop the melodramatics. “And now you’re one of us. It all worked out the way it was supposed to.”

“But it almost didn’t,” Gemma said. “And I know that you all couldn’t care less about me or the other two girls you killed, but don’t you care at all about your own lives? If I had died, what would you have done?”