One of the good things about living in Dulwich was that Scarlett did have plenty of friends and they all lived very nearby. There were two girls from her class in the same street and there was also a boy – Aidan Ravitch – just five minutes away. It was Aidan who had prompted her to cross the road.

Aidan was in his second year at The Hall, yet another local private school, and had come to London from Los Angeles. He was tall for his age and good-looking in a relaxed, awkward sort of way, with shaggy hair and slightly crumpled features. There was no uniform at his school and he wore the same hoodie, jeans and trainers day in day out. Aidan didn’t understand the English. He claimed to be completely mystified by such things as football, tea and Dr Who. English policemen in particular baffled him. “Why do they have to wear those stupid hats?” He was Scarlett’s closest friend, although both of them knew that Aidan’s father worked for an American bank and could be transferred back home any day. Meanwhile, they spent as much time together as they could.

The accident happened on a warm, summer afternoon. Scarlett was thirteen at the time.

It was a little after four and Scarlett was on her way home from school. The very fact that she was allowed to walk home on her own meant a lot to her. It was only on her last birthday that her parents had finally relented… until then, they had insisted that Mrs Murdoch should meet her at the school gates every day, even though there were far younger girls who were allowed to face the perils of Dulwich High Street without an armed escort. She had never been quite sure what they were so worried about. There was no chance of her getting lost. Her route took her past a flower shop, an organic grocer’s and a pub – The Crown and Greyhound – where she might spot a few old men, sitting in the sun with their lemonade shandies. There were no drug dealers, no child snatchers or crazed killers in the immediate area. And she was hardly on her own anyway. From half past three onwards, the streets were crowded with boys and girls streaming in every direction, on their way home.