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.

‘You saw Lindsay Mullen meet Rose Shepherd at the Riber Tea Rooms in Matlock Bath, didn’t you?’ said Hitchens.

‘No comment.’

But the answer came more quickly this time, more confidently. Donnelly knew who they were talking about again. It seemed to Fry that he hadn’t known Lindsay Mullen’s name until then. Somehow, that made her killing worse. It appeared even more cold and merciless. She had been an anonymous woman eliminated without a second thought. And the two children? What about them? They’d just been in the wrong place at the wrong time.

‘There’s one thing that really puzzles me,’ said Hitchens. ‘How did you know who Lindsay Mullen was?’

Donnelly smiled. ‘No comment.’

‘I mean, did you have advance information about the meeting taking place? Did you have a description of Mrs Mullen that enabled you to identify her? Or did you listen in to their conversation somehow?’

A shake of the head. ‘No comment.’

‘Whichever it was, the organization seems to have been exceptionally good, very well planned.’

Donnelly gazed down at the table, but Fry could see the smile on his face. If his eyes had been visible, she guessed that she’d see in them that he was laughing – laughing inwardly at the stupidity of the police.

‘Or was it only luck, Tony?’

His head came up then, and his eyes narrowed at Hitchens. ‘I don’t know what you’re talking about.’

‘It was Rose Shepherd you were looking for, wasn’t it? And you stumbled on Lindsay Mullen at the same time. That must have been very convenient for you. It made the job a lot easier, I imagine. What would you have done otherwise? Were you planning on breaking into Miss Shepherd’s house and interrogating her until she gave you the information you wanted?’

Donnelly glared at his solicitor. ‘What’s this shit?’ he said.

‘Detective Inspector Hitchens, could you clarify what my client is accused of? We don’t understand this line of questioning.’

‘We’re conducting enquiries into the murder of Miss Rose Shepherd, who was shot and killed in Foxlow in the early hours of Sunday morning. We’re also investigating the deaths of Mrs Lindsay Mullen and her two children, who died in a fire at their home in Edendale on the following night. And we’d like to know from your client the names of his associates in these offences.’

There was quite a long silence after Hitchens’ statement. When Donnelly responded, it was with a smirk that would have got him a punch in the mouth at one time, before interview rooms were equipped with tape recorders and video cameras.

‘No comment,’ he said.

Fry fetched two coffees into the DI’s office. It was something she wouldn’t normally let herself be caught doing. But they both needed some caffeine. Even so, she took care to avoid the door of the CID room, in case anyone saw her.

‘Thanks, Diane,’ said Hitchens.

He was spinning his swivel chair from side to side, making it squeal at the end of each turn. It was a habit he had when he was angry or stressed.

‘What’s the plan, sir?’

‘I’ll let Donnelly stew for a while, then I’ll have another go at him later.’

‘He’d never heard Lindsay Mullen’s name before,’ said Fry. ‘I could tell from his face when you asked him about her.’

‘Do you think so, Diane?’

‘Yes, I do.’

Hitchens stared out of the window as he took a sip of coffee and put the cup down quickly. It was too hot, as usual.

‘I’m inclined to agree with you. It was almost the only time we got a genuine reaction out of him. He was surprised. And then he thought it was funny. It makes things more difficult for us, doesn’t it? It suggests there were more people involved than we first thought.’

Fry sat down, balancing her own cup on her knee. ‘What do you mean?’

‘If Donnelly doesn’t know anything about Lindsay Mullen, it means the Darwin Street job must have been given to someone else.’

‘Really?’

‘Well, it’s good practice. Separate teams, with no contact between them. Neither team knowing what job the other is doing. There’d be much less chance of them implicating each other that way. That would explain why Tony Donnelly doesn’t even know Lindsay Mullen’s name. He probably only read about her in the papers, like everyone else.’

‘I suppose it could also be the reason why the arson seemed so much less professionally executed. There were always too many differences in approach for them to fit together comfortably. So we have a second suspect, you think?’

‘At least.’

‘Nikolov?’

‘I don’t see how. There’s no indication that he left the farm during the last couple of days before he died. More likely, he picked up a newspaper, or turned on the radio, and heard about Rose Shepherd’s killing. Then he drank himself to death.’

‘He followed her to Derbyshire, then followed her into death?’

Hitchens blinked a little. ‘Well, Nikolov was no hit man.’

‘Who, then? I wonder if that could have been someone recruited at short notice. They can’t have expected to identify the Mullens so quickly after finding Rose Shepherd. There’d have to be a last-minute change to their plans.’

‘A local villain, dragged off the street for a one-off job, cash in the pocket?’ said Hitchens, brightening noticeably.