Kirsty swore softly. She was shaking. The wave of stress and anxiety swept through her. There was only one thing that would keep it at bay. She drew the curtains, let the towel fall to the floor, and reached into the bedside drawer. A few minutes later, as the buzzing pleasure came in wave after wave, tears escaped from the outer corners of her tightly closed eyes and rolled down her cheeks and into her ears.

It was the first evening that Gillard had arrived home at a reasonable time since the case began. Now at nine o’clock they lay entwined on the sofa, each trying to read. Sam was engrossed in 101 Tastes from the Subcontinent: Mrs Roy’s Guide to Indian Cuisine. It was published just a few weeks before her death and was now, according to the papers, flying off the shelves. Gillard had been flicking through a true crime exposé of American serial killers in the 1980s, but when Sam looked up to tell him about a particularly interesting Goan curry, she saw that he had dozed off.

She smiled to herself, and laid her book on the end table. In repose, her husband looked younger than his fifty years, more boyish, less rugged, less capable. She wanted to stroke his face, but it was such a rare and precious moment to see him like this, almost vulnerable. His mouth was slightly open, no sign of his usual bunched jaw muscles. The stress, the professionalism, the cynicism, the gut instinct were all packed away somewhere, in some mental filing cabinet, ready to be retrieved at a moment’s notice.

The gentle tone of his phone indicated a call. The device lay on the dining table ten feet away, but his eyes flicked open immediately. Instant wakefulness, immediate awareness. He stroked her thigh as he untangled his legs from hers and went to pick up the mobile. She continued to watch him, broad shoulders flexing, legs astride as he shifted into work mode.

‘Gillard.’ A slight softening in his stance in the next few seconds indicated to Sam that the caller was a familiar and trusted contact.

‘Okay, Claire. That’s great news.’

After he hung up, he responded to Sam’s quizzical expression by saying: ‘We found a DNA link at the crime scene. Someone who was at the punch-up outside the pub on Saturday night looks to have been present at the Ashtead Common crime scene just a few hours later. He left a single hair on Mrs Roy. And he’s got some previous for affray. Claire has got an address and is going round to make the arrest right now.’

‘Seems like a breakthrough.’

‘Yes. If she gets him in the cells tonight, we will be able to interview him first thing tomorrow.’

Half an hour later, just as they were getting ready for bed, Sam stood at the front bedroom window in her underwear looking through a tiny gap in the curtains. ‘There, she’s at it again! She’s got her binoculars looking up here.’