Keeping the gun to her head, he grabbed her by the hair with his other hand and began dragging her along the passage, looking into each room as they went. She had to go with him, or be pulled off her feet. His right leg was stiff, she saw, with a length of wood strapped to the side of his knee as some kind of splint. He was probably in a lot of pain. And she was responsible for it. But he wasn’t ready to kill her quite yet.

They reached the kitchen. Caldwell wasn’t there. When he’d left and where he’d gone Wada couldn’t guess. He might never have heard their exchanges for all she knew.

The door of the next room was closed. The Irishman kicked it open with his uninjured leg. It was a bathroom, fitted with a cupboard, hand-basin, loo and claw-footed bath that all looked about as old as the kitchen furnishings. The Irishman let go of Wada’s hair for a second, pulled a set of handcuffs out of the pocket of his parka and closed one cuff round her right wrist. Then he forced her to the floor, bent over her and snapped the other cuff round the downpipe under the basin.

‘When I have found Caldwell and killed him,’ he rasped into her ear, ‘I will come back to question you, Wada. And you will answer my questions, I promise you. You will answer every one of them.’

As he stood upright, he winced and steadied himself against the rim of the basin. Seeing her chance, Wada drew back her legs and aimed a kick at his splinted knee, using all the force she could summon. Something cracked under the impact. The Irishman cried out and fell. The gun went off as he toppled. There was an explosion of plaster from the ceiling above the basin.

Then there was another crack, as the Irishman’s head struck the curved rim of the bath. He thumped to the floor, his head taking a second heavy blow. The gun was jolted from his hand. It slid across the tiles and came to rest against the wall beneath the window.

The Irishman’s eyes stared sightlessly at Wada. He didn’t move. A pool of blood appeared beneath his head, slowly widening. Wada scrambled to her feet, sliding the handcuff up the pipe. But she was unable to stand fully upright because it snagged against the underside of the basin. And from that position the gun was out of her reach.

‘Mr Caldwell,’ she called out. ‘Come here. To the bathroom. It is safe. I need your help.’

The house was enveloped in silence, magnified and muffled by the snow outside. Nothing moved. There was no answer from Caldwell.

‘Mr Caldwell!’