She laughs, caught in a rush of discovery she hasn’t felt for lifetimes. If she can break gravity in a single patch of air, there must be a way to break everything. Tear the city apart from the inside. All she needs to do is give the simulation inputs it wasn’t set up to handle, until she triggers a bug catastrophic enough to make it crash.

Elated, she climbs back through the mirror into Der Zentaur. Brigitta glares at her. “What are you doing behind my bar?”

Thora waves her arm through the mirror. “What’s a hole in reality doing behind your bar?”

Brigitta blinks, confused. Thora remembers the same look on Jules’s face and feels a tug like the pull of an old scar.

She sighs. “I know. You don’t know what to say.” She pats the barmaid on the shoulder and walks out, already planning her next move.

Thora pries another padlock off the Hohenzollernbrücke and hurls it down into the river. She waits for the faraway splash, then turns back to check her progress. Three-quarters of the fence stretches empty behind her; the rest still gleams with mismatched and sentimental eyesores. Soon, it will be clear, and the simulated river will have two tons of unexpected metal to contend with. “See how you handle that, universe,” she mutters. She crouches again, maneuvering her wrenches into the shackle of the next lock. She’s so absorbed that she doesn’t immediately notice when someone walks past her humming a familiar tune.

Her head turns. The man is walking away, but she’d know his gait anywhere. She watches Santi head for the opposite bank. The last thing she wants is to face him. But she burns with the need to know where he’s going, if he’s trying to find his own way out.

She packs her wrenches away in her rucksack and follows. Staying at a safe distance, she tracks him to the Odysseum, camouflaging herself in the crowd as he heads inside. He does a leisurely circuit of the planetarium and the hall of astronauts before turning into the quiet corridor with the room marked “Under Construction.” Thora watches as he sits down on a bench opposite the image from the Kepler telescope and starts sketching. Every so often, he looks up, as though he’s waiting for someone. For her, Thora assumes as she ducks out of view; but why not wait at Der Zentaur, where she would know to find him?