Her lungs were starting to burn as she approached the eighth floor. Beyond the next landing was the scuffling sound of shoes on concrete. Gwen she slowed her progress and peered out carefully.

The early evening sun fell in a brilliant shaft of light, angled through the whole area. Concrete reinforcement wire poked out of blocks in the centre. Gwen blinked in astonishment. She could see through the unfinished floor, and again through the next three floors below that. On a cross-beam in the centre stood Jack. He was balanced, apparently unconcerned by the dizzying gap below him, with his pistol trained on the far side of this shell of a room.

Wildman had picked his own way carefully over the fretwork of connecting girders, and now scrambled over the partly constructed exterior wall and onto the raised wooden and metal framework that surrounded the building. He had to use both hands to balance, and then to grasp the weathered steel of the scaffolding and hoist himself out onto the ledge. His beige coat no longer clung tightly to him. It rippled in the breeze that whistled through the carcass of the building. Gwen could see that the raincoat was actually too small for Wildman, and the arms had ridden up above his wrists to reveal the soiled cuffs of his grey suit.

Wildman stood on the pale brown scaffolding platform. He turned to face Jack. The race up the building and the subsequent scramble across this floor had exhausted him. He took deep, desperate breaths of air. Several metres to his left a stretch of the zigzag laddering straddled the side of the building, an even more precarious route down than the unfinished emergency stairs. To Wildman’s right, the battered plastic opening of a long debris chute yawned ominously, ready to devour whatever was dropped in and to regurgitate it many floors below into another, unseen yellow skip. Wildman couldn’t seriously be considering either of those exits, thought Gwen.