We were just turning back again when there was a sudden scuffle. The end of the alley finished in an even narrower short cobbled passage, just wide enough to admit a person, leading out to another ordinary street. Two dark figures burst from the passage mouth and ran headlong towards us. They were wearing hooded tops and their feet and hands seemed freakishly huge. Mr Rainbird pulled me aside and stood in front of me, but one of the runners knocked him as he pounded by and we both staggered against the wall of the nearest garden. Mr Rainbird caught me and I heard myself give an involuntary squeak of fear. Then the runners were gone out of the gate at the other end, leaving the echo of loud laughter in their wake.

‘It’s okay, they’re just kids,’ Mr Rainbird said. I stood still for a second longer, my head close to his chest, imagining that I could hear his slow, steady heartbeat. He was used to the behaviour of huge children, of course, living as he did in the tidal waves of them at Jack’s school. I detached myself carefully, breathing hard. The sudden eruption of threat in this enclave of prettiness had frightened me more than I wanted to acknowledge. There I had been, thinking of the city as a vastly amorphous but basically benign organism; now there seemed to be only a thin veneer of order crusted over a boiling crater of unrest. I shook my head to dispel the unwelcome idea.

‘Are you all right?’

‘Yes,’ I said. The alley was quiet again, with its lighted windows just showing behind good curtains and the white glimmer of flowers in the dark. We walked back to the car and Mr Rainbird drove me home. The pavements surged with people all the way and the roads pulsed with steady gouts of traffic.

‘I’ll call you,’ he said, when we drew up outside the house. He kissed me lightly on the cheek.

‘I’d like that,’ I said.

I noticed that he waited while I fumbled with my keys and let myself in, and only drove off when the front door shut safely behind me.

The house was very silent and empty. I went round methodically switching on lights and drawing the curtains, with unease crawling in my veins. It was gone eleven but I was sure Penny would still be up. She answered her phone on the second ring.

My anxiety irrationally focused on Cassie. ‘Is everything all right?’

‘It’s late, Sadie.’

‘Is Cassie asleep?’

‘Yes, of course she is. Hours ago.’

I exhaled with relief. ‘Good. That’s fine. And what are you doing?’