Mary drank too much red wine from a plastic cup, then climbed over the dunes to look over the sea. It was late but still light, the sky’s violet and gold reflected in the wet sand and ebbing sea. Behind her she heard the children complaining as they were rounded up for bed, the first chords of guitar music, the strains of a protest song. The empty beach stretched south for seven miles towards Brinkbonnie village.

When he climbed up the dune and sat beside her, she was not surprised. Perhaps she had wandered away from the crowd in the hope that she would be followed. It was that sort of night: hot, romantic. She was ready for excitement and some sort of sexual adventure. When she saw who it was, she was not surprised, though at the time almost anyone would have done. She had been aware of him all evening and had sensed as he prodded cindered sausages with a long fork that he was ready for rebellion, too.

“Hello,” he said. “Are you all right?”

“Fine,” she said. She smiled at him.

“You look a bit lonely.”

“No,” she said. “ Just enjoying the evening.”

She stood up suddenly and ran down the steep bank of sand, sliding and tumbling, sending up a rainbow of fine sand that gleamed in the last of the light. She was wearing loose, clown’s trousers and a T-shirt in black and white stripes. When she reached the water, she looked back at him. Later she thought that if she had carried on up the beach without turning to see if he was still there, staring at her, none of it would have happened. He would have gone back to the fire, shaken the sand out of his trainers, and under the orders of the bossy women done his duty with black bin bags and rubber gloves. He would have gone straight home to his wife. But she did turn round, and he saw it as a challenge to follow her. He launched himself from the top of the dune and ran at full-tilt without stumbling. She was impressed by the run. She had expected a more cowardly descent, a sedate walk perhaps, with his hands behind him in case he fell. As he ran towards her she turned and walked away up the beach, just on the edge of the tide. He fell in beside her as if he were there by chance, as if in the whole vast expanse of the beach it was pure coincidence that he happened to be there.