She smiles at Mum and me as we sit down in the chairs next to her. But it’s a polite smile. The type you give strangers. ‘Can I help you?’ she asks. I feel Mum tense next to me.

‘Gran, it’s me, Saffy.’

Her eyes light up. ‘Saffy!’

‘And your daughter, Lorna,’ says Mum.

‘Lolly!’

I wipe a tear that has seeped out of the corner of my eye, hoping nobody has noticed. I’ve never heard her call my mum by that name before and I wonder if she’s regressed into the past, to when Mum was a little girl.

‘Yes,’ says Mum, the relief evident in her voice. She takes Gran’s hands in hers. ‘It’s Lolly.’

‘I’m sorry, Lolly,’ says Gran, her face crumpling. ‘I’m so sorry.’ Tears run down her crinkly cheeks and my heart feels like it’s going to break.

‘Why are you sorry?’ asks Mum, kindly, her eyes full of concern as they flick to mine and then to Gran again. ‘You don’t have to be sorry for anything.’

‘Are the police coming back?’

‘Now don’t you worry about the police. I’ll handle them,’ says Mum, firmly, producing a tissue, magician-like, and handing it to Gran. She always seems to have one about her person, goodness knows where in her tight outfits. Gran takes it and wipes her tears away.

‘Mum,’ she hesitates, throwing me a worried look, ‘can I ask you if you remember a man called Neil Lewisham?’

Gran blinks up at Mum with her big eyes but doesn’t say anything.

‘What about Sheila Watts?’ probes Mum.

‘Sheila Watts?’

‘Yes. You mentioned a Sheila before, remember?’

Gran turns to me, still dabbing at her cheeks. ‘Jean hit her over the head. Jean hit her over the head and she didn’t get back up again.’

‘Jean hit Sheila?’ I ask.

‘No. Jean hit Susan. Susan died,’ she says, sounding impatient now, like we should know what she’s talking about.

Susan? Who the bloody hell is Susan?

‘Is Susan the body in the garden?’ I ask gently, not wanting to spook her.

‘I don’t know if she’s in the garden,’ she says, frowning, shredding the tissue in her hands. ‘I don’t know where they put her.’

‘Who’s they, Gran?’

‘The people who came to take her away, of course. They weren’t just going to leave her there bleeding, were they?’

From the corner of my eye I see Mum’s perplexed expression.

‘So Susan is dead?’ I ask. My stomach is clenched with anxiety. Gran’s memory is like a stained-glass window that has shattered: the fragments mean nothing in isolation, but everything if they were put in the right order. ‘Do you remember her surname? This Susan?’

‘Wallace. Her name was Susan Wallace.’

I hear Mum’s sharp intake of breath.

‘And you’re saying Jean killed Susan Wallace and buried her in the garden.’