‘And you wonder why I married Isobel instead of you,’ he said, low and bitter. ‘At least she has stood by me, these forty years. She’d never betray me like this.’

Rosalind considered him for a moment, then crossed the room to the glass display case and opened it. ‘You should know that this is a fake. And if you don’t already know that, then that means Isobel sold the real one.’ She held the jeweller’s loupe out to him. ‘You might want to ask her what she did with the money.’

Hugh stared at her, like he wasn’t sure whether to believe her, for a long while. Then he snatched the miniature magnifying glass from her hand and stalked out of the study.

Leaving his phone sitting on the desk, as she’d hoped.

She waited to hear his footsteps disappearing down the stairs, then picked it up. The passcode was easy – he’d used the same one for everything forever. She hoped he hadn’t had the foresight to delete what she was looking for.

She scrolled through and found it, her pulse pounding as she lifted the phone to her ear and listened.

And then she knew for sure.

In the end, agreeing on a plan was easy.

Caro said, ‘What would Dahlia do?’

‘Dahlia would catch the killer,’ Posy replied.

‘Dahlia would let the killer catch themselves,’ Rosalind corrected her, thinking of all the times Dahlia had brought a murderer to justice. ‘She’d make them confess everything.’

‘She’d also have Detective Inspector Johnnie on standby to arrest them,’ Caro pointed out.

Rosalind sighed. ‘Yes. She would.’

‘You’ll speak to Larch?’ Posy asked. ‘You’ve connected with him most.’

Apart from the bonding session he’d had with Posy’s bra, she supposed that was true. ‘I’ll speak to Larch. After we put everything else in place.’

‘What do we do?’ Caro asked.

And together, they hammered out the details of the plan.

‘The signal will be the gong,’ Rosalind repeated, as they went over things one last time.

‘Just after midnight,’ Caro confirmed. ‘Nobody will miss that.’

‘As long as they don’t miss these.’ Posy waved the envelopes she’d finished addressing in the air. Good to know that the writing desk in the Snug wasn’t just for show – it had been equipped with almost everything they needed for their plan.

As if Lettice Davenport herself had prepared the ground for what was to come.

Rosalind supposed that, in a way, she had. Without her, none of this would have happened. She’d started this mystery, and now she was going to end it. What had begun with script pages from The Lady Detective, and that fatal dinner, would end with a variation on Dahlia’s J’accuse plan from the end of Poisoner’s Delight. They’d changed only enough so that, hopefully, their target wouldn’t realise what they were doing until too late.