‘We used to have rats in the house,’ Alice said, staring at the bricks a few inches in front of her face. ‘They would put traps down, but sometimes they wouldn’t work properly, and the poor things would still be alive. Father would have the servants take them outside and drown them in the rain barrel.’ She swallowed hard. ‘I always felt sorry for them.’

‘Better them than us,’ Ashes said. The water was now at least a foot high, covering the swarmers, but it still boiled with the swarmers’ struggle to escape. ‘You realize it is going to be us in a few minutes?’

‘I’ll open the door and let the water out,’ Alice said.

Ashes thought about the geometry of that for a moment. ‘And where will I be standing when this happens, pray?’

‘Cats can swim, can’t they?’

‘I’ve never had occasion to find out! Besides, I’m only half cat.’

‘It’ll be a learning experience, then.’

‘I absolutely refuse!’

‘You’ve got a couple of minutes to think of another plan, then.’

They waited in silence as the water rose. The surface no longer boiled, but Alice wasn’t sure if that meant the swarmers had drowned, or if they were just too deep underwater. To be safe she gave it until the rising tide was nearly at her toes.

‘Have you thought of anything?’

‘I’m still thinking,’ Ashes said desperately.

‘Too late.’ Alice drew in a breath and dropped off her handhold.

She had learned to swim in the beaches along Long Island, on summer vacations and visits to her parents’ friends. The Atlantic was always cold, even on a sunny day, but this was something else entirely. It hit her like a punch to the gut, driving the air from her lungs. She managed to kick enough to keep off the bottom – the thought of putting a foot down among the mass of drowned swarmers turned her stomach – and fumbled for the latch on the door. Behind her, Ashes had taken a flying leap from her shoulder, tried to get a hold on the brickwork, and ended up in the water anyway. He paddled desperately, shrieking incoherently.

Alice tried to work the latch, but her fingers had gone instantly numb. Her hands felt as though they were encased in blocks of ice. She pressed down with the palm of her hand and gave the handle a hard tug, but the door didn’t so much as budge. Sudden realization dawned.

‘Too much water on this side.’ Her teeth were chattering. ‘I can’t . . . open it . . . too heavy . . .’