“What does all that mean?” she asked, looking up at Lydia.

“That as long as there are four of them, it doesn’t matter who they are. Any of them can be replaced.” Lydia shook her head sadly. “Even Penn.”

“So why would Diana say that?” Gemma rubbed her forehead and slouched in the seat. “She said if I killed Penn, the curse would be broken. Why would she lie about that? We were about to leave anyway.”

“Maybe she didn’t lie,” Lydia said.

“But with the scroll—”

“No, I mean Diana said, ‘If you tried to kill Penn, then you wouldn’t need to break the curse,’” Lydia recited carefully. “Maybe she just meant that if you tried to kill Penn, you’d lose.”

“Diana knows I’m young, I probably appeared weak, and she rightfully assumed that if I was capable of killing Penn, I already would have.” Gemma lay back down on the seats and squeezed her eyes shut. “So if I went up against Penn, she would kill me, and when I’m dead, I’m free of the curse.”

“But that could be wrong,” Lydia said, trying to sound hopeful. “I mean, Pine’s still working on these translations. We’re not finished, and like I said, we could’ve misread them.”

Now, as Gemma swam the cold depths of the ocean, the futility of it hit her hard. Diana/Demeter had been their last big hope, and she had been a bust. The big clue she’d given them had been nothing more than a taunt.

The joy of being in the water had given way to a familiar desperation and an ever-growing hunger. Her practice transformations had the unfortunate side effect of making her hunger stronger, and the day away from Capri, battling the watersong, hadn’t helped either.

It was September now, and the autumnal equinox was only weeks away. Gemma would have to feed soon, or she really risked losing control, especially if she wanted to keep practicing her transformations.

She’d begun to suspect that part of the reason she’d been so crazed when she’d killed Jason Way was because she’d been starving. That’s why she had a better handle on the monster now, and probably why Liv seemed to have a better grasp of morphing. Liv ate constantly, so she was never really hungry, and that probably made her better at control when she shifted in and out of the monster.

As Gemma was swimming, plunging down in the darkness at the bottom of the ocean floor, frightening the fish and crabs lingering at the bottom, she felt something following her. A shadow stayed behind her, and Gemma sped up. The last thing she needed was to get in a fight with a shark this morning.

But no matter how fast she went, the dark shape in the water stayed behind her. Gemma had swum out past the bay, but now she circled back, heading toward land. She didn’t glance back, but she felt it gaining on her. An electricity in the current, the subtle shifts of the approaching predator, spurred her on.

The land was too far, but a large rock jutted out of the bay. Gemma raced toward it, and she pushed herself out of the water and gripped crevices in the stone. Her torso was completely above water, but her fish tail was submerged. It would be slippery, deadweight if she tried to haul herself out, and she finally looked back before beginning the climb up the rock.

Penn surfaced from the water, laughing in a way that sounded like the cackling of a crow. “Oh, Gemma, you’re so funny when you’re scared.”

Gemma relaxed, but she still hung on to the rock. “I thought you were a shark.”

“You’re lucky I’m not,” Penn said as she floated next to her. “Or I’d be devouring you right now.”

“Why were you following me?”

“I wanted to find out how things went yesterday.” Her full lips were pressed into a blood-red thin smile. “How was your little adventure?”

Gemma looked toward the shore and pushed her wet hair out of her face. The sky above them had really started to lighten, turning purple and pink in anticipation of the sunrise.

“What are you talking about?” Gemma asked at last.

“You went somewhere yesterday, somewhere away from the water.”

“How do you know?”

“We can feel it. We know whenever anyone gets too far away,” Penn said. “You could die, and I’ll have to come up with another replacement.”

Gemma rolled her eyes. “And I know how you’d hate to replace me.”

“Where were you?” Penn asked, but it sounded more like a demand.

“I told Thea. I went to Sundham to visit Harper.”

“Sundham’s not that far inland.” Penn narrowed her eyes as her black hair pooled in the water around her. The water was at her chin, and Penn had never looked more like a sea monster.

Gemma shrugged. “Well, that’s where I was, so I don’t know what to tell you.”

“I don’t know what you’re playing at, Gemma, but it’s a very dangerous game. You don’t want to mess with me.”

“I’m not,” she insisted.

“So then tell me where you went?”

Meeting Penn’s gaze defiantly, she said, “No.”

Penn pushed herself above the waves, balancing on her tail so her entire torso was showing and she could stare imposingly down at Gemma. “I am so sick of this. I have enough going on with Liv, and this whole rebellious act of yours is getting old. You need to learn your place.”

Gemma’s fangs were itching in her mouth, and she decided not to try to contain them. She might not be strong enough to kill Penn, but there was only one way she’d know for sure. And she was sick of dealing with Penn, sick of being a siren, sick of dreading the next time she’d have to feed, so even if she couldn’t stop Penn, at least Penn would stop her.

One of them would die today. It almost didn’t even matter to Gemma anymore which one it was, as long as this was over.

Gemma smiled as she spoke, revealing her jagged fangs. “Maybe it’s time for you to learn your place.”

“You little bitch,” Penn said, smiling wider. “Bring it.”

THIRTY-FIVE

Hostile

Gemma lunged at Penn, who didn’t move or even try to block her. As she wrapped her fingers around Penn’s throat, she felt them lengthening, the bones crackling as they grew. As Gemma tightened her grip around Penn’s neck, they both plummeted underwater, falling toward the bottom of the ocean.

Penn’s lips pulled back, stretching around her fangs, and her face began to change shape. Her cheekbones grew more pronounced, her eyes receded farther back, and her charcoal hair thinned. Her face had shifted into the full monster, reflecting the same changes that were happening to Gemma’s.