All the other killers? Are you sure that’s not because she’s no more a murderer than you are?

Yes, Simon was sure. Especially now he was in an interview room with her at the nick where he’d worked for most of his adult life, a backdrop against which he’d seen many guilty people and many innocent ones. Isobel Sturridge moved, spoke and dressed like a good girl who wouldn’t dream of causing any trouble: neat, short hair like a fitted cap around her head; a flowery blouse with a shiny pink trim around the collar and cuffs; apricot-coloured flat shoes that fastened with a strap and a buckle, like the shoes girls in Simon’s class at primary school used to wear. Even her perfume smelled innocent: light and flowery. But the reek of her guilt was stronger.

Simon couldn’t work it out. All the aspects of Isobel Sturridge that ought to have made him fear he’d erroneously cast her in the role of killer only convinced him more: it was her. The more benign she seemed, the stronger grew his certainty that she’d committed five murders.

The clothes. He’d start with the clothes.

‘When you spoke to Kim Tribbeck outside the RGI on Tuesday, 6 January, you were dressed very differently to how you’re dressed today: jeans, black hoody, trainers. Quite masculine. Yet here you are in a floral blouse, a skirt, schoolgirl shoes. Is that because you were in disguise when you went to the cancer ward on 6 January?’

Isobel said nothing. A tear trailed down her cheek. Sam was fidgeting, no doubt worried they were bullying her. She’d refused a lawyer. Simon wondered if part of her plan was to look bullied: the helpless victim of insensitive interrogation. He rejected the idea straight away; her unhappiness had nothing to do with their words or behaviour. She gave the impression of being a distraught person trapped in a sealed bubble. Simon felt that he couldn’t get to her, though there were fewer than ten inches between them.

‘You were in disguise as Faith Kendell, I believe. Where did you get that name from?’

She shook her head.

‘Isobel,’ said Sam gently. ‘If you don’t know what we’re talking about—’