“So simple.” Ovid rubbed its jaw. “Love never ceases to amaze me. Well, all you have to do is …”

“I know, cry a joyful tear to resurrect each of the billions of people I’ve killed,” she said glumly. “And I have until sunrise.”

“Sounds like a busy night, even for a party animal like you.” The robot squinted at her. “You know, before now I had never considered how insignificant your eyes are.”

“Thanks.”

“For a girl whose tears do what yours do, your eyes are really very ho-hum. One begins to wonder—does it even need to be your eyes that shed the tears?”

“What do you mean?”

“I’m about to say something important, something I can recognize only now that I’m liberated from my wretched mortal form. This body”—it rapped softly on Eureka’s wounded chest—“doesn’t matter. If I were you, I’d give it up.”

“And where do you propose she finds another?” Ander asked.

The robot leaned back on the lounge and cradled its head in its hands. It crossed its feet and put them on Eureka’s lap. “Where Atlas would feel it most.”

“I told you, I don’t think Atlas can feel.” Eureka paused to consider what she’d just said. She touched her neck, which used to connect her to Diana and the most primal love Eureka had ever felt. It was bare now. “That’s it.”

“What?” Ander said.

“Delphine told me Atlas’s heart wasn’t tuned for love,” Eureka said.

“That sounds like something you say when the person you love doesn’t love you back,” Ander said. His tone pleaded for her to meet his eyes, to deny that she didn’t love him. But she wouldn’t.

“She was speaking literally,” Eureka said. “Atlas’s heart is out of tune.”

“Is Atlas a robot like Ovid?” William asked.

“I don’t think so,” Eureka said, “but his heart was another one of Delphine’s experiments. She did something to remove love from his range. If I can possess Atlas the way he possessed Brooks, the way he tried to possess you”—she looked at Ander—“if I can make him feel joy, make him cry with love, it would destroy him.”

Ander studied her closely. “You used to want to redeem yourself, to fix the world. Now all you care about is killing Atlas? Do you know what it would mean to go inside him?”

“Her redemption and his death are tantamount,” Solon said. “If Eureka succeeds in making Atlas weep with joy—she is right—the tears would be formidable.”

“Powerful enough to reverse the Filling,” Esme said in a quiet voice that suggested even the intimidating gossipwitch was sickened by Atlas and Delphine’s plan.

“But what about her?” Eureka murmured. If Delphine was the darkness inside Atlas’s shadow, she was the true enemy. Shealways had been.

“That is the question I’ve been waiting for,” Solon said.

Eureka thought back to her last game of Never-Ever, played lifetimes ago on the bayou, when Atlas had used Brooks to hurt her, and she knew what she would do.

“We never see betrayal coming from the ones we love most,” she said, and pretended not to see Ander shiver. She reached for one of the gossipwitch pipes, twirled it between her fingers. “But how do I possess him?”

Ovid pointed at Ander. “Ask him.”

“No,” Ander said. “I won’t do it.”

“You came here to help me,” Eureka said. “What does Solon mean?”

“You die in this plan. If you go into Atlas’s body, there will be no way out.”

“Don’t die, Eureka,” William whimpered, and climbed into her lap.

She rocked her brother wordlessly and glared over his head at Ander.

“There has to be another way,” Ander said. “I’ll go with you. We’ll fight Atlas and Delphine together.” He gestured at Ovid. “We’ll use their weapon against them.”

“They have eight more machines just like Ovid, filled with millions of ghosts,” Eureka said. “It wouldn’t even be a fight.”

“You underestimate me,” Ovid said, in a voice Eureka couldn’t identify.

“You already tried to kill yourself once,” Ander said. “I won’t let you quit again.”

“I don’t belong in the world I have to save,” Eureka said. “This is the only way.”

Ander shook his head. “I meant it when I said I won’t live in a world without you,” he said. “Eureka, don’t you—”

Don’t you love me? She knew that was what he wanted to say. She took his hand. “If you weren’t a sun and I weren’t a black hole, I would.”

Ander’s eyes were damp. She had never seen him cry before. When he turned away, Eureka was relieved. She was consumed by what she had to do, by the thrill of her discovery about Atlas. She thought of Delphine, more in love with her dark powers than she could ever be with another soul. Maybe they had more in common than Eureka realized.

She felt pressure in the palm of her hand. When she looked down, Ander was pressing the coral arrowhead, the tool Atlas used to enter his possessions, into her palm. It was stained with Ander’s blood.

She rested her forehead on Ander’s chest. They stayed like that for a moment. The throb of his heartbeat made Eureka’s own heart race. Her breath picked up and stabbed her broken ribs. She pulled away. She gazed into his eyes and wanted to ask what he would do after she left, so that she could carry an image of him being okay in her mind. But that was selfish, and there was no answer, because everything anyone might do after Eureka left this cave depended on whether she succeeded or failed.