Orla hesitated, but then she folded her umbrella and unlocked the front door. ‘Come on inside, then. But take off your shoes, please. I don’t want my carpet ruined.’

They took off their coats and prised off their shoes and followed Orla into the living room. She stood in front of the red-marble fireplace with her arms folded, her lips tightly pursed. She didn’t invite them to sit down on the large grey leather sofas. Behind her, on the mantelpiece, a framed photograph of Garrett was smiling cheerfully at the back of her head.

‘We need you to tell us who was driving Garrett’s car on the morning that he died,’ said Katie.

‘Garrett, of course. Who else?’

‘Well, no, he wasn’t. And we have evidence that he wasn’t.’

‘What evidence?’

‘We have CCTV footage that plainly shows another man sitting in the driving seat of Garrett’s car. Not only that, it shows you coming out of the house and talking to this man before he drives off.’

‘I don’t believe you.’

‘I think a judge will believe us when we show that footage in court.’

‘I’ve no comment to make. I know what you gardaí are like. You’ll tell any kind of lies to coax a false confession out of people. And then you’ll conveniently lose all the proof that you lied, the same as you did with Sergeant McCabe and Lynn Margiotta and Majella Moynihan.’

‘Orla, there’s no doubting this footage. It’s as clear as day. I’m asking you now to tell me who was driving Garrett’s car on the morning that he died.’

‘I’ve no comment.’

‘All right, you’ve no comment. But we have a screenshot of this fellow’s face and even if you won’t tell us who he is, it won’t take us long to identify him, and then we can ask him why he was driving Garrett’s car.’

‘I still have nothing to say. I’m not going to let you trap me into admitting something that I haven’t done.’

‘Garrett was sitting in the front passenger seat that morning, wasn’t he?’

‘No comment.’

‘It must have been him, because he was found in his burned-out car at White’s Cross only half an hour later. But why would he agree to be a passenger in his own car? Was he threatened? Or did he not agree at all? Was he drugged? Or was he knocked unconscious?’

‘No comment.’

‘Orla, you told me how devastated you were by Garrett’s death. But you did also tell me that you resented his affairs. Is that what this was all about? Were you trying to teach him a lesson but it went too far? Did you hire this fellow simply to frighten him, or to give him a bit of a beating maybe, by way of punishment?’