“The building frame,” said Henry.

“I have to get home,” Jane said. “Christ, if it’s come this far—”

She started towards the door. It was like trying to walk in a moving subway train.

“Look,” said Marge Case softly.

A wave was passing through the floor, through its substance, a neat sine wave a few inches high. The floor tiles buckled, or popped away from where they were glued. “Good God,” said Marge, and she giggled. “Floor surf.”

It happened in an instant.

The floor lurched under Jane, like a plane in turbulence, and she was thrown to her knees. She landed hard, her knees and the balls of her hands taking the impact. She felt as if she had been punched. The shock of it, the physical power, was like a violation.

And now the floor tipped, and she was sliding. Someone screamed. She looked for Henry.

Suddenly equipment was flying off the shelves on the walls, electronics boxes and tools and glass dishes, raining down. And the people were clinging to the floor, or skidding down the sudden slope, trying to stay on their feet.

She saw a heavy set of weighing scales come tumbling down in a neat parabola, and hit a lab-coated man in the back of the neck, evoking a sharp, clean snap. He fell forward, arms and legs loose, and rolled down the tilted floor.

The lights flickered. One of them exploded in its housing in the ceiling. Then they failed, and she was in darkness.

Jane was still sliding down the floor, in pitch darkness. It was a childhood nightmare, a mundane world turned monstrous, dragging her down into some pit she couldn’t even see.

Everyone seemed to be screaming now. More explosions from above. A crash, a stink she couldn’t recognize, and she found herself coughing. Christ alone knew what chemicals they kept in here; there had to be a danger of toxic fumes, fire.

She scrabbled at the broken floor; her fingers closed around the lip of a dislodged floor tile, and she hung onto that. The tile ripped her nails, but she wasn’t falling any more.

Somebody came skidding down the floor, and hit her side. The impact was huge, uncontrolled; a thick hand scrabbled at her clothes, trying to get a grip. She knew she couldn’t hold this new weight, and her own.

She should kick this guy away. She knew that’s what she should do.

He didn’t get a hold. He fell away into the dark, sparing her the decision.

Now there was a new series of deep, grinding cracks. Light from below; a throaty explosion of collapsing brickwork, the grind of tearing metal. She risked a look down. The wall beneath her had broken up, and huge chunks of it were falling away, letting in the daylight. Glimpses of the car park, maybe fifty feet below, the cars still parked in their mundane rows.