To his left was the front door and immediately ahead of him the door to the drawing room. To his right a passage led towards the house’s interior: dining room, kitchen, library and a Victorian conservatory that Gabrielle used as her studio. He stood absolutely still, his hands raised ready to defend himself. He could hear nothing. In the corner of the hall, the tiny red eye of the movement sensor winked at him. If he was not careful, he would trigger the alarm himself. That had already happened twice elsewhere in Cologny since they moved in – big houses wailing nervously for no reason, like hysterical rich old ladies behind their high ivy-covered walls.

He relaxed his hands and crossed the hall to where an antique barometer was mounted on the wall. He pressed a catch and the barometer swung outwards. The alarm control box was hidden in a compartment behind it. He reached out his right forefinger to enter the code to switch the system off, and then checked himself.

The alarm had already been deactivated.

His finger stayed poised in mid-air while the rational part of his mind sought for reassuring explanations. Perhaps Gabrielle had come down after all, had switched the system off and had forgotten to turn it back on again when she returned to bed. Or he had forgotten to set it in the first place. Or it had malfunctioned.

Very slowly he turned to his left to inspect the front door. The gleam of the lamplight reflected in its glossy black paint. It appeared to be firmly closed, with no sign it had been forced. Like the alarm, it was of the latest design and also controlled by the same four-digit code. He glanced back over his shoulder, checking the stairs and the corridor leading to the interior of the house. All was still. He moved towards the door. He tapped in the code. He heard the bolts click back. He grasped the heavy brass handle and turned it, then stepped out on to the darkened porch.