The view from the swarmer’s eyes, spinning wildly as it caromed down the stairs, was enough to turn Alice’s stomach, and she hurriedly abandoned its senses and opened her real eyes. For a few moments it was a struggle not to vomit, staring fixedly at the ceiling and reminding herself that it was not her who had been falling down the stairs. Once she had her rebellious gut under control, she reached out for the swarmer again, cautiously, ready to will it out of existence if it was badly hurt.

To her surprise, it was standing placidly on the firstfloor landing, apparently no worse for wear. They really are like little rubber balls, Alice thought. Then she laughed out loud as another thought occurred to her. It seemed a little – undignified, perhaps, but after all, there was no one to see, and it would certainly be easier than going down the steps one at a time.

A moment later, the swarmer sprinted to the edge of the landing and took a flying leap off the first step, tucking its legs away and hitting the fourth step down with such force that it bounced nearly to the low ceiling. This time Alice stayed with it, laughing out loud at the sensation of caroming down the stairs like a stray tennis ball, bouncing at an angle off the landing wall and on down another flight of stairs, ricocheting wildly between the banister and the wall.

The swarmer was now three storeys below her, on the ground floor, and as it got to its feet Alice noticed that the distance was having an effect. If moving the swarmer was like moving a limb she’d never known she had, it now felt as though that limb was wearing a lead weight. It wasn’t painful, but it took effort, and the weight got heavier the further away the creature got.

At the moment, it was still bearable, and she looked around with the swarmer’s eyes to orient herself. The bottom of the servants’ stairs let out into the passage beside the kitchen, and the door had apparently been open, because the swarmer had bounced right through it and off the opposite wall. In one direction, the kitchen was as dark and silent as always. The other way led to a door that was always closed, which led into the boiler-room domain of Mr Black.

Except, tonight, it wasn’t closed. There was a narrow gap between the door and the door frame, just wide enough to admit the body of the swarmer. Gaslight from inside spilled out of the narrow opening. Shuffling a little closer, Alice could hear voices, just on the edge of comprehensibility.