She checked her map. Coming south from Sheffield, the M1 passed through part of Derbyshire, entered Nottinghamshire near Pinxton, then crossed back over the border again for the last stretch towards the airport. The confusion of jurisdictions made no sense in policing terms. It was an anomaly that someone always pointed out when the subject of merging police forces came up.

East Midlands Airport lay right by the M1, between junctions 24 and 23A. From the north, the Mercedes would take 24 if it was heading for the airport. Right now, it was approaching the slip road into Trowell Services.

Watch for him pulling off.

Have we alerted our neighbours?

Control rooms are in the loop.

One result of the M1’s waywardness was that Trowell Services lay over the border in Nottinghamshire, despite being within two miles of Ilkeston nick. Permission had to be obtained for an operation on neighbouring territory, and officers would have to keep the control room at Sherwood Lodge informed as well as their own at Ripley.

But the Mercedes went past the services and drove another eight miles down the motorway. The helicopter’s observer kept up a running commentary to guide the units converging on the suspect.

Leaving the motorway now.

The vehicle came off at junction 24 and took the fourth exit at the roundabout on to the A453 in the Donington Park area. At the next roundabout, it would have to stay on the same road and bear right at the lights into the airport. But it didn’t do that.

Turning into the Travelodge. It looks as though he’s parking up.

OK, take up positions and await FSU.

Fifteen minutes later, Hitchens gave Fry the thumbs-up, and a big grin. Their suspect was in custody.

‘So you don’t want to tell us about Rose Shepherd,’ said Hitchens, watching Tony Donnelly across the interview-room table.

‘I’ve got nothing to say.’

They’d been trying for a long time, struggling through the kind of interview that Fry hated – the kind that made her think of banging her head repeatedly against a wall. Good only when it stopped. In fact, she had a suspicion the average wall would crack long before this suspect.

Donnelly and the duty solicitor stared back at the detectives across the table. They had an air of being two visitors at a zoo, wondering when these strange creatures were going to do something more interesting.

‘What about Lindsay Mullen, then?’ said Hitchens.

Donnelly hesitated slightly before he answered. ‘No comment.’

‘Where did you first see Mrs Mullen?’

‘No comment.’

‘Did you even know her name, Tony?’

‘No comment.’

Fry could see Hitchens gathering his thoughts before the next question. Like her, he’d seen the expression that had briefly passed across Donnelly’s face when Lindsay Mullen’s name had been mentioned. Surprise, incomprehension. A lack of recognition. Just for a moment, before he’d trotted out the standard response.