Then Molly arrived. He recognized the engine sound of her car, the erratic gear changes, the violent braking, before he turned to see it stop, next to his van, by the quay. She climbed out easily and quickly. She did not seem to him to be old. She was grey now of course, and a little plumper, but not very different from when they had married. She had the same energy.

She could tell that he was disturbed because he allowed himself to show that he was pleased to see her. He even kissed her, briefly. They had led self-contained working lives long before such partnerships were common, and his telephone call the night before had been unusually demanding and uninformative.

“Can you come down to stay for a few days?” he had said. “ Do try to come.”

“I am pleased to see you,” he said.

She looked surprised, but did not say anything. It was one of her qualities, he thought, that she knew when there was nothing to say.

She had been wearing a pair of old plimsolls for driving. She dressed in baggy trousers and strange, loose jerseys, but for comfort, not for effect. Her appearance had never bothered him, even when he had had to mix socially with men whose wives were smart and sophisticated. Now he did not notice it. She changed into a pair of wellingtons, put on a plastic mac, and they began to walk.

“You didn’t say much last night.”

“No, I was using the observatory phone. There’s an extension in the warden’s flat. I was afraid of being overheard.”

“I heard about it all on the radio,” she said. “It said that someone was helping the police with their inquiries. Does that mean that the police know who committed the murders?”

“They think that they know.” He had spoken more sharply than he intended, and added: “I suppose it’s inevitable that they should have arrested the boy. But the policeman in charge of the case, Savage, is unimaginative, stubborn. I believe that there’s more to the investigation than he realizes, but I can’t convince him. I worked with him once before when I was with the Home Office, so he asked for my help. Now, because I can’t agree with him, he doesn’t want me involved at all.”

“Tell me what happened,” she said. “The man was already dead when you arrived on Saturday?”

“Charlie Todd. Yes.”

So he described the events of the weekend to her. As he answered her questions, tried to help her to understand what it was like to be there, he brought some order to the chaos of his memory. He remembered important details, unconnected snatches of conversation.

“Tell me about the people,” she said. “What were they like? How did they all get on?”

“I don’t think that they have anything in common, except the observatory. John, the warden, is quiet, conscientious, a bit weak. I should think that Elizabeth is the stronger. You’ll meet them on the island. You’ll be able to judge for yourself.”