Palmer hoped he was onto something. All he wanted to do was solve the case and be home in time to spend Christmas day with his son. Looking at the clock on the incident room wall he knew he would have to cancel attending the carol service with them that night. Letting out a deep sigh Palmer picked up the phone and dialled his wife’s number. He’d been looking forward to hearing his son sing for weeks and, to make matters worse, he knew his bitter disappointment would be matched by his child’s. But it was his job. He didn’t have a choice.

The conversation was brief and, when it ended, Palmer called Elly Hale over to help him comb through the evidence. ‘Wade and Matlock,’ he said turning to his screen, ‘I want us to go through it all again.’

‘Another late night then?’ She sounded almost pleased.

‘Yes. Another night away from my wife and son.’ Palmer was in no mood for gentle flirting. ‘Let’s get this done and hopefully we might make it home before midnight.’ He handed the files over without looking at her.

‘Very well, sir.’ Elly adopted a more serious tone and returned to her desk feeling dejected. Suddenly the prospect of being over at the CCTV control room scanning through hours of footage seemed more appealing than it had.

By half past nine she was struggling to keep her eyes open, so was both grateful and surprised when Palmer appeared holding two cups of coffee.

‘Peace offering.’ He handed one over, which Elly happily accepted.

‘It’s no bother.’ She took a sip of the hot black coffee, which burnt her tongue and the inside of her lower lip. ‘You’re stressed. We all are,’ she added, putting the coffee down.

‘Still, I shouldn’t bite your head off. We’re all in the same boat.’ Palmer put his cup down next to hers and pulled a chair up to her desk. ‘Found anything?’

‘Wendy Matlock had lots of hobbies.’ She displayed a number of photographs to prove her point. ‘She loved outdoor pursuits and was extremely active.’

Palmer waited patiently for her to get to the point.

‘Dennis Wade was also somewhat obsessive. His son has told us that he spent all his time in the bookshop and very little time at home.’

‘Yes,’ Palmer encouraged, having no idea where she was going with it.

‘Well, they are both obsessive.’

Palmer scratched his head.

‘I think maybe there is something in that. Maybe the killer is punishing people who spend more time at work, or concentrating on hobbies, than they do at home. Maybe that is the link.’ She sat back in her chair not knowing whether she felt triumphant or foolish.

‘Okay. So you are suggesting this is about neglect?’ He was trying to unpick her theory.