She opened her eyes on a half-moon in a starry sky, and when she finally got out, saw that the lawn was already frosted white and the driveway shingle glinted. She stretched, feeling as she had at the end of a shift as a junior doctor in A&E. Everything ached. She let her mind linger on the prospect of a large gin and tonic, and a hot bath. Kieron was home, so there might even be something prepared for supper.

She put her hand to the doorknob, and as she did so, shivered slightly, with a vivid sense of the cat Mephisto emerging out of the darkness to weave round her ankles, miaowing softly in welcome, waiting to be let in. But Mephisto was in his grave, which was still faithfully visited and kept up by Felix.

Felix? Another moment of panic before she remembered that he was safely staying with his friend Marcus, sharing the construction of a Lego Hogwarts Castle.

‘Hey, I’m home!’

There was a groan from the kitchen.

Kieron was sitting at the table, left leg up on another chair and what appeared to be a wet tea towel draped across his knee.

‘What have you done?’ Cat dropped her bag and coat on the sofa and went to her husband.

‘It was so stupid. I was just coming down the stairs . . . my phone rang and I slipped.’

‘When you say coming down the stairs, you mean running?’

‘I’m not five, Cat, but it wasn’t my fault, and it bloody hurts.’

‘I’m trying to establish the facts – and will you stop shielding your knee with both hands, that’s what kids do.’

‘Why are you being so mean to me?’

She got up and went to the fridge. ‘Here, drink this.’

‘Is it vodka?’

‘Water with ice. You’ll be dehydrated.’

‘I pity your patients if you’re like this all the time.’

‘I’m not. All right, let me do what I sometimes do with children – if I put my hands behind my back and keep them there, will you show me your injury? Honestly, Kieron.’

He made a face but lifted his hands away. His left knee was very swollen and livid, though the skin was unbroken. She put her hand out and he winced back.

‘It’s really painful, Cat.’

‘It looks it but I have to touch to find out exactly where it hurts most. I’m not going to put any pressure on.’

‘No, don’t. I think I’ve broken my kneecap.’

‘I doubt it, that’s actually quite hard to do. Does it hurt here? Here?’

Kieron pulled his leg back at her touch and yelped but she went on gently prodding and testing.

‘OK, I’m going to put another ice pack round it, you’re going to hobble into the sitting room and put it up on the sofa, on a pile of cushions, and then I’ll get you some painkillers.’