‘I’d like to see it,’ Callie said quietly. ‘Please don’t make me beg.’

A sigh, a shake of my head, but I took out my phone, calling up the relevant app, and selected the appropriate recording. I’d taken the backup flash drive from Dan’s laptop on the night of his death, making sure to permanently delete the only other copy of the recording from Dan’s cloud storage. Later that same evening, I transferred the flash-drive contents to my private phone before completely wiping and reformatting the drive. Belt and braces. I was confident I had the one and only recording of the study at the time Dan died, and that was the way it was going to stay.

Fast-forwarding to the relevant section, I handed the phone to Callie. She immediately sat down on the sofa, her attention entirely focused on the recording. I sat beside her, waiting for the inevitable fallout. Callie pressed play and brought the phone closer, her gaze intense.

The short clip showed Sephy, wide-eyed and open-mouthed with panic, plunging a thin-bladed letter opener in Dan’s back before wiping the handle clean.

Callie frowned at me, her downturned lips twisting in puzzlement. Without saying a word, she played the clip again.

‘What’s the issue?’ I asked. ‘It seems pretty straightforward to me.’

‘You kept this because—?’ asked Callie.

Damn it. My face burned red. Callie nodded knowingly.

‘Whatever you may think of me, Callie, I tried to shield your mum, but as you can see she—’

‘Mum didn’t do it,’ she said softly.

‘Callie, come on. You can clearly see—’

‘How many times did you watch this, Tobey?’

I frowned. ‘Once with George present. Once by myself to make sure I’d transferred the recording properly.’ What difference did it make? The recording wasn’t going to change, no matter how many times I viewed it.

‘You thought you knew what you were looking at so you didn’t bother to watch it properly.’ Callie pressed play again, only to immediately press pause. ‘The recording starts with the knife in Mum’s hand, but look at it. The blade is already bloodstained. And look at Mum’s face. She’s horrified.’

‘Because she’s just realized what she’s done,’ I prompted as gently as I could.

Pursing her lips, Callie again hit play then pause in quick succession. ‘Dan was stabbed twice, once in the jugular, once in the back, but check the knife blade. Only one drop of blood falls from it onto the back of Dan’s dark jacket.’

Callie touched play once more. We both watched as Sephy stabbed Dan with slow deliberation, then used the inside hem of her blouse to wipe the handle of the letter opener.

‘So the recording only started after she’d already stabbed him once,’ I said. ‘It still shows she did it.’