A message, no doubt. She took a small plastic evidence bag from her shoulder bag, and carefully picked up the item. The BMW was idling on the other side of the road, and she crossed over and resumed her position in the back seat.

‘Find anything, ma’am?’

‘A pair of women’s knickers.’

Their heads swivelled to look at her in precise symmetry. ‘Let’s have a decko,’ Worrell said, with a bit more than professional enthusiasm.

‘Use your imagination. I’m sure you have plenty of stock images stored there.’ She rang the incident room to report her find. Otara was put on the line.

‘We have a dashcam ANPR camera just two hundred yards away,’ he said. ‘Bracketing vehicle movements five minutes either side of the message time, we got a quite manageable seventeen hits that we are currently processing. Stay in position.’ He hung up.

Claire relayed the message to Worrell and Blunt. She looked out of the window and saw on the side road Adrian Singer walking down the road towards them. It didn’t look like a planned walk on such a chilly spring day because he was in a lightweight jumper, shorts and Crocs. He looked up and down the road, and rubbed his arms for warmth, before walking over to the BMW.

Claire lowered the rear window and said: ‘Hello. Remember me?’

‘Yes. There were some boy racers going up and down the road just a few minutes ago. I could hear them even from the back of the house,’ he said.

‘I’ll keep an eye out,’ she replied.

‘So what are you doing?’

At this point Blunt slid down his window and forcefully told the man to return immediately to his home. Singer recoiled at the directness of the order, and radiated indignation as he retraced his steps.

‘…and Blunt by nature,’ Claire said archly.

‘He could blow our cover, ma’am.’

‘Detective Constable Blunt, I fear it is your adolescent driving that is responsible for that.’

‘I can’t believe it! This was the man who said he had never loved anyone like he loved me. This was the man who made me go to the gym before work, who threw away and burned half my wardrobe because it was too frumpy, the man who went through my phone deleting the phone numbers of any male friends, the man who deleted all friend requests on Facebook. He claimed to be so besotted with me, the new slimmed-down me, that he couldn’t ever look at anybody else.’ Ellen’s sobbing tirade poured out.

‘I know he exploited you terribly, but if I may—’

‘Do you know, Craig, what he did for me on the night of my birthday?’

‘Ellen, please.’ Gillard had the tricky task of trying to coax this scorned and deeply wounded woman away from her pain, and to focus on the here and now. He had very little time and needed to get from her every piece of information that might save Sam.

‘Gabriel made me a beautiful birthday cake, cherries and icing and everything. All gluten-free too. I don’t know how he found the time. He must have loved me, mustn’t he?’