As he climbed down he had his back to her, and when he reached the floor he paused for a few seconds, still holding on to the ladder, as if he were listening to make sure that the gardaí had all gone downstairs.

Her voice sharp and clear, Katie said, ‘Keep your hands raised up and turn slowly around.’

Even under his black puffer jacket she could see the man’s shoulders tense.

‘I said – keep your hands raised up and turn slowly around. You’re under arrest.’

He turned to face her. He was fortyish, with spiky grey hair, baggy cheeks, and glasses. Even though he had his back to the light, Katie recognized him at once as the man who had been driving Garrett Quinn’s Jaguar on the morning when Garrett had been burned to death.

‘Patrick!’ she shouted. ‘Patrick – get yourself up here, will you? Quick as you can!’

The man stared at her through his thumbprinted lenses and then he said, ‘Holy Christ and all the fecking Holy Ghosts, it’s you! Talk about the worst fecking luck! I swear to God I’ll kill that fecking optician!’

Katie heard no answer from downstairs, so she shouted out again, ‘Patrick! Sergeant Mullally!’

Still no answer. If they couldn’t hear her, she would have to reach inside her raincoat for her TETRA radio to call them for help, but the bespectacled man was sure to be armed, and so she wanted to keep her pistol aimed at him as steadily as she could.

‘What’s your name?’ she demanded.

‘What the feck is my name any business of yours?’

‘It’s my business because you’re under arrest for threatening behaviour and on suspicion of homicide, and because you’re under arrest you’re required by law to give me your name and address.’

‘Aha. But the law also says that you’re required to show me your ID, girl, since you’re not in uniform. You could be fecking anybody for all I know.’

‘You know who I am.’

‘Ah, but you could be your twin sister. Or maybe some other bean-garda who’s the bulb off of you.’

‘Are you going to tell me your name?’

‘Why don’t you fecking guess? I’ll give you a clue – “Sharky”.’

Katie said, ‘I’m going to back slowly downstairs and I want you to follow me, keeping your hands up. If you don’t follow me, or if you make any suspicious moves, I won’t hesitate to shoot you. Do you understand?’

The man suddenly lost his temper. ‘You fecking scrubber!’ he screamed at her. ‘You cailleach! How the hell did I miss you? You should be lying in your fecking coffin by now with all your relatives weeping around you!’