‘I didn’t see any of them go up there. Maybe I miscounted when I saw them coming out of their cars. But, okay, let’s go up and make sure. We don’t want the landlord coming back to find a half-baked Riordan hiding in his hot press.’

He pushed the door open wider and started to climb the stairs, holding his pistol high up in front of him. Katie and Detective O’Donovan followed him.

At the top of the stairs there was a narrow landing, with two doors on either side. It smelled even stuffier than the bars downstairs. At the far end there was a stained-glass window in amber and red, with two broken panes that had been blocked with cardboard.

Sergeant Mullally turned the handle of the first bedroom door and then kicked it open. Inside there was a single unmade bed, a side table and a cheap plywood wardrobe. He looked under the bed and then flung open the wardrobe doors, but there was nobody under the bed and nothing in the wardrobe but blouses and dresses and wire coat-hangers.

They went on to the next bedroom, and the next, and the next. In one of them, the bed had no mattress and the rest of the room was stacked with boxes. In another, the bed was neatly made and there were photographs on the wall of children and elderly grandparents. But there was nobody hiding in any of them.

‘Definitely must have miscounted,’ said Sergeant Mullally, holstering his pistol. As he did so, one of his unit shouted up the stairs, ‘Sarge! They’re calling for some backup outside!’

‘Right with you!’ Sergeant Mullally told him, and he clumped his way back down the stairs to the bar. Detective O’Donovan holstered his pistol, too, and followed him, ducking his head down as he went through the door.

Katie took a last look around the landing and was about to go after them when she heard a soft scraping sound, and then a dull bump, and another scrape.

She stood still, her pistol half-lifted, listening. At first she couldn’t be sure where the noises were coming from, but then she heard another bump, and she realized it had come from the ceiling. She stayed where she was, waiting; and then suddenly the attic door flapped down, swinging from side to side. With a creak of hinges, a sliding aluminium ladder came down, and two legs appeared, in faded blue jeans and worn-out brown boots.

Katie held her pistol in both hands and aimed it directly at the foot of the ladder. She didn’t shout out for Detective O’Donovan or Sergeant Mullally because that would warn the man climbing down that she was waiting for him, and it was highly likely that he was armed.