The scurrying sound starts on a cold Sunday evening, when she’s comfortably slouched on the sofa and on a second glass of wine. Her gaze lifts to the ceiling unworried; this is a top floor flat with the only thing above it an unused attic. They get the occasional bird, and bat, and who knows what other wildlife half the time.

She continues to watch the ceiling as the burrowing sound continues, picturing a Labrador happily digging a hole in the park at the bottom of the road. She knows it’...