His colleague frowned. ‘Meaning?’

‘Was Rebecca Watkins already having an affair with Eden’s husband, and they hatched a scheme between them for Rebecca to seduce Eden and become her lover, get her to change her will and then kill her, making it look like she’d disappeared?’

‘The flaw in that, as I see it, boss, is how would Rebecca know that Eden would be up for being seduced?’

‘Fair point,’ Grace said. ‘Maybe it only started as a friendship and they became closer? I don’t know, it’s just another hypothesis. But it seems to me that we have two people in deteriorating relationships – Niall Paternoster and Rebecca Watkins. We know from Emily Denyer’s investigations that Niall Paternoster is skint, apart from the small change he makes as a taxi driver.’ He paused. ‘With me so far?’

‘I’m on your bus.’

Grace smiled and went on. ‘Rebecca and Niall are lovers. Niall’s wife has a considerable net worth. Somehow, whatever Eden Paternoster’s proclivity, Rebecca Watkins succeeds in seducing her, and then taking it further, to the point where they are planning a future life together – at least, in Eden’s mind. Rebecca convinces Eden to move all her assets out of Niall’s reach and, for extra security, she gets her to change her will in her favour. Then Rebecca plots with Niall to murder Eden, making it look like she has simply disappeared. But Niall has screwed it all up, leaving a trail of evidence.’

‘But they’ve still been smart enough to dispose of Eden’s remains, leaving us with a “no body” murder investigation – perhaps aware how hard they are to prove. Remember all those crime novels and true crime DVDs in their house?’

‘I reckoned we had enough evidence on her husband, until the will popped up,’ Grace said. ‘But, of course, it provides another motive if he knew about this more recent will.’

‘Do you think we might have enough for the CPS to consider a “conspiracy to murder” charge against both Paternoster and Watkins?’

Grace shook his head. ‘Not yet.’

His phone rang once more. It was Taylor again. ‘Sir, subject and Rebecca Watkins have entered a pub. Orman’s only two minutes away and is going there now.’

Ending the call, Grace shook his head. This was the level of professional surveillance he needed for this case. Hopefully Orman would get a line of sight on the couple and be able to lip-read their conversation. ‘Pewe,’ he said. ‘What a bloody idiot.’

Sure, he understood that, as the overall head of Major Crime for Sussex Police, Pewe had to make decisions on deploying his limited resources. But drugs came down from Liverpool all the time – the docks were a major point of entry for them into the country. You’d bust one lot and another supply chain would take their place. But this was a potential murder, one he felt close to cracking, and the ACC had taken away his most valuable resource. At least, a small win, he’d been able to get them for today.