While she was confronting him, Detectives Caffrey and O’Sullivan were going from one man to the other, patting the pockets of their coats. They lifted out two automatics, a Browning and a Sig-Sauer, and four knives, including a machete.

‘Where are they?’ Katie repeated.

‘Who d’ye mean?’

‘Are you thick or what? You know full well who I mean. Your boss Barry Riordan and Thomas O’Flynn.’

‘Upstairs,’ one of the other men told her, a short, skinny Afro-Irish fellow with frizzy hair. ‘Second floor. It’s the only room in the building with chairs and a table.’

‘Well, thanks a million for that,’ Katie told him. ‘Ronan – Jamie – would you check if our backup’s turned up yet? If they have, tell them to come in and arrest these clowns, would you?’

‘Hey, we’ve done nothing,’ protested one of the men. ‘We only came in here for a smoke, like.’

‘Trespassing on private property carrying loaded firearms and knives is hardly what I’d call “nothing”,’ Katie told him. ‘You’re going to be lucky if you end up in Rathmore Road for less than a year.’

She saw that the staircase was over on the left-hand side of the reception area. It was unlikely that the lift was working, and even if it were, the sound of it would give Thomas O’Flynn and Barry Riordan an early warning that somebody was coming.

She said, ‘DI Fitzpatrick?’

If the two gangsters were upstairs by themselves, she didn’t think that she and Robert would have any trouble in arresting them. She knew that Thomas O’Flynn never carried a gun, any more than he ever carried a phone.

They climbed the stairs as quietly as they could, even though the treads were covered in crunchy grit. When they reached the second-storey landing they saw that one of the office doors was wide open, and they could hear voices.

Katie paused, her pistol raised in her right hand, and listened. Then she turned to Robert and frowned and silently mouthed the words, Who’s that talking?

They weren’t men’s voices. They were women’s, and they were sharp and angry. Katie could hear one of them saying, ‘You don’t think you deserve this? Really? You never thought you’d die all peaceful in your sleep and go to Heaven, did you? You pathetic shitehawk!’

‘Come on,’ said Katie. She and Robert stepped into the office with their pistols gripped in both hands and Katie shouted, ‘Freeze!’

She could hardly believe the sight that met them. The office was bare except for a dusty boardroom table and six chairs. It was gloomy in there, because the windows were covered with broken venetian blinds, but a crucifix of sunshine lay across the middle of the table, which gave it the appearance of an altar.