‘They will assume you bought it on the darknet. In all likelihood they will have already confiscated your home computer and be checking it. They will be examining all your computers at work. But that is more complicated because of solicitor-client privilege. Privacy protection is so important in your profession, so it’s likely your computer will be hard to crack.’

‘Well, I didn’t buy arsenic from anywhere. So that’s all right. They won’t find anything.’

John Thornton leans back in his chair. ‘Good. Good. Well, they can’t nail something on you that you haven’t done. Sounds like you’ve nothing to worry about.’

‘I wish I had your confidence. I can see why people call the police pigs.’

DS Badminton and DI Sarah Jones burst into the room. DI Sarah Jones is a big-boned woman with pale blonde shoulder-length hair and broad shoulders. DS Badminton looks perpetually worried.

They sit down opposite us. DS Badminton presses a switch to begin the recording.

‘Let’s begin. DS Badminton and …’ he stares across at DI Jones.

‘… DI Jones,’ she announces clear as a bell. ‘Present.’

‘Also,’ he points at me, ‘Saffron Jackson.’

He points at John. ‘John Thornton.’

Then he re-arrests me. The words pierce into me again. Panic rises inside me.

‘Where did you get the arsenic?’ Sarah Jones asks, leaning forwards across the plastic table, face hard. Arms folded.

‘I didn’t,’ I reply.

Her broad lips curl. ‘We know you’re lying.’ There is a pause. A long deliberate pause, designed to intimidate. ‘Where did you get the arsenic?’ she repeats.

I shake my head. ‘I didn’t get any arsenic. I don’t know what you’re talking about.’

Her eyes harden. ‘You’ll get a lower sentence if you co-operate and tell the truth as soon as possible.’

I smile a short, clipped smile. ‘Check my computer. Check my house. Check anything you like. I’m clean. Whiter than white.’

John Thornton coughs. ‘Please explain to my client why you are treating her like this. She denies the charge vehemently.’

DS Badminton and DI Jones exchange glances. A buzzing sound trills in Jones’ earpiece. She frowns as she listens to whoever is speaking to her through the earpiece. She nods her head.

‘OK then. We found arsenic in a glass bottle beneath your kitchen sink. Your fingerprints and no one else’s on the bottle,’ she announces. She leans back and folds her arms. A flicker of a smile. Raised shoulders. ‘And we found traces of arsenic in your mother-in-law’s blood. Pretty conclusive if you ask me.’

Anger explodes like a volcano inside me.

‘She hated me. She sent you a letter, didn’t she? She set me up. I think you had better look into this case properly. I think you had better do your job.’