‘It’s most likely Miller had more than one mobile,’ she reasoned. ‘Especially if he was playing so many angles.’

‘It’s not so likely he would have been picking up last night, though, eh?’

Catherine felt her eyes bulge.

‘I tried the number from my desk,’ Laura confirmed. ‘Got a hello. I asked, “Who is this?” and they hung up right away.’

‘But Miller was definitely Cairns’ source. Abercorn confirmed they knew he was touting to Locust as well as to Bob.’

‘I don’t doubt he was. But that’s not who phoned Cairns while we were with him in that café on Thursday morning.’

Catherine’s head was starting to implode. If Cairns had a second informant in play, it was a very fly move to let everyone believe his source was Miller: what better way, in fact, to protect the remaining one than by making people think his info came from elsewhere? But if it wasn’t Miller who tipped off Cairns about the shipment, how come Miller’s pal Whitaker was in place ready to tan the jeweller’s?

‘I am sorry,’ Laura intoned sincerely. ‘I’m not habitually sneaky, just a daft moment of impulse. I didn’t feel I’d got off to a very good start here in Glasgow, but this is hardly gaunny rectify that, eh?’

Catherine could see tears forming in her eyes.

‘You’re doing fine. What gave you the idea you’ve made a poor impression?’

‘Just … low confidence, I suppose. Not feeling quite myself.’

‘Is it the change of city? Why did you apply for a transfer?’

Laura paused, longer than it had taken her to fess up to snooping Cairns’ phone.

‘Bad break-up,’ she said.

Catherine could tell the brevity was down to knowing she could only get out a few words at a time without crying.

‘Bad relationship.’

There was bitterness to this second issue: self-doubt, regret, pain, and so much anger.

Laura looked her in the eye, just for a quarter of a second: long enough to let her see it.

Catherine reached out a hand and clasped it around Laura’s clenched fist.

‘You’re doing fine, hen,’ she said quietly. ‘You’re doing fine.’

Then the windscreen shattered.

Catherine shuddered bodily in fright as thousands of pieces of glass suddenly filled the air around them. She looked briefly at Laura, then behind, aware that the rear windscreen had gone too.

She caught a microsecond’s glimpse of a man in a mask levelling a pistol through the rolled-down window of a red car, then ducked as he pulled the trigger again.

They flattened themselves as low as they could across the front seats, hearing further rounds zip above their heads, pinging into metal and smashing the side windows. The Rover lurched on its suspension cradle as two of the tyres were hit, then she heard the gunning of an engine and the squeal of rubber on tarmac.