He found it impossible to pinpoint the direction from which the voice was coming. And for a moment he was tempted. What business was this of his, after all? He could get in his car and drive to Duncan Hunter’s house, which was only a couple of miles away as the crow flew. He could sweep Cassie into his arms and take her home with him and first thing in the morning they could get a plane south. He even began planning where they should go. To see Fran’s parents, of course. They were lovely people and always eager to see their granddaughter. He imagined the warm welcome there would be. Hot chocolate for Cassie and tea for him. Toast and honey.

Then he heard another sound, a moan stifled by the weather. He thought it must come from the hatchery, but it was impossible to tell. He shouted. ‘Where are you?’ and felt the sound of his voice vibrate around the place, washed away by the rain.

‘This won’t look like murder.’ The killer’s voice was reasonable. ‘This will be put down as an accident at sea. You know how many ships have been lost out here on the Rumble. You know what the tide would do to a body in this water.’

And suddenly Perez’s mind cleared and thoughts were firing into his brain, fast and sharp. It was adrenaline perhaps. A need to survive. Not for himself, but because he had an obligation to Fran’s child. The killer would have left the building and would be standing between him and his car; the invitation to walk away was a trap. Of course Perez wouldn’t be allowed to leave here alive. Not now that he knew the identity of the murderer.

‘Rhona Laing is a fine sailor,’ Perez said. ‘Nobody will believe in an accident. Not in calm weather like this.’

‘Suicide then.’ The killer was dismissive. ‘Why not? Even better because folk will think she killed Markham and Henderson.’

Another silence. Perez strained to pick up the slightest noise. A footstep or a clearing of the throat that would mark the presence of the murderer. This was a horrifying version of Blind Man’s Bluff. But the ground was so soft that boots would make no noise. Perez kept as still as he could. The tide must be on the turn, because the water washed against the pier now and not over it. The sound was quite different. It sucked on the shingle on the beach.