He takes in a sighing breath. “Perhaps it’s a gift. To be able to see the possibility of a better world.” His eyes fix her. “But I don’t believe it can work like you say, that we could step into it so easily. No. We have to work to make it.”

Thora lets the thought settle in her. It wakens a memory, like a vision seen in flames: sitting by her mother’s bedside after her stroke, desperate to reach into the machinery and make it work again. The desire that led her off the path she thought was hers and onto a new one. The path that eventually brought her here, to a ninth-floor treatment room on a rainy afternoon in Cologne: to an old man who is looking at her with infinite patience, as if their roles have been reversed.

“You are busy, Doctor,” Mr. López says. He opens the door. Thora has to fight the urge to ask him to stay. It burns her strangely that their time together is so limited. Don’t leave me alone in this, something in her cries.

“I’m not supposed to say this,” she tells him, “but you’re my favorite patient.”

Mr. López gives her a somber look. “If I am dying, please just tell me.”

She laughs. “Nah, you’ve got a good ten years in you yet. Five of those with working hands, if you keep doing as I say.” She takes his hand. As they shake, his gaze lingers on the tattoo on her wrist.

Thora holds the door for him. “See you next time,” she says.

He blinks at her, confusion flickering across his face. “Next time,” he agrees, and carefully pulls the door closed.

At the end of the day, Lily leans around the doorframe. “Boo. You almost finished? We’re going to Chlodwigplatz to join in the craziness, if you want to come.”

Carnival. A week of wild, drunken street parties, with the flimsy historical excuse of letting off steam before Lent. The idea of joining in makes Thora want to jump out of the ninth-floor window. She rubs her eyes as she switches her computer off. In the black mirror of the screen, her face looks lost. There’s a thought she can’t grasp, lingering in her mind like the smell of smoke in her hair. “Sorry, I can’t tonight.”

“Plans with Jules?”

“Jules is away. I have plans with the sofa and a tub of ice cream.” She looks through her fingers at Lily. “I know it’s antisocial. But—”

“But you’d rather watch Contact for the fiftieth time than hang out with us actual real humans. It’s okay. I get it.” Lily shakes her head, mock-offended. “Look after yourself,” she adds as she turns away.