‘Commuters from Central London, arriving home to find their street is a crime scene,’ said Moss.

‘But I live just there,’ one man was saying, pointing with his briefcase to a house two doors down. His face was flushed and weary, his thinning hair plastered to his head. When Moss, Erika and Isaac drew level with him at the police tape, he looked to them, hoping they had come to give different news.

‘I’m DCI Foster, the senior investigating officer, and this is Dr Strong, our forensic pathologist,’ said Erika flashing her ID at the uniformed officer. ‘Get in contact with the council, organise these people beds for the night.’

‘Very good, ma’am,’ said the uniformed officer, signing them all in. They ducked under the police tape before they could get involved with the commuters protesting at the thought of a night on camp beds.

The front door of 14 Laurel Road was wide open, and lights blazed from the hallway, which was busy with CSIs wearing dark blue overalls and face masks. Erika, Isaac and Moss were handed overalls, and they suited up on a patch of shingle in the tiny front garden.

‘The body’s upstairs, front bedroom,’ said Moss. ‘Victim’s mother came over to feed the cat. Thought he was away on holiday in the south of France but, as you’ll see, he never made it to the airport.’

‘Where is the mother now?’ asked Erika, stepping into the thin overalls.

‘She was overcome by the shock and heat. Uniform just went with her to University Hospital, Lewisham. We’ll need to get a statement when she’s recovered,’ said Moss, zipping up her own suit.

‘Just give me a few minutes to examine the scene,’ said Isaac, as he pulled up the hood of his own suit. Erika nodded, and he went off into the house.

The heat, volume of people and bright lights all helped to tip the temperature in the upstairs bedroom to over forty degrees centigrade. Isaac, with his team of three assistants and the crime scene photographer, worked in an efficient, respectful silence.

The victim lay naked on his back in the double bed. He had a tall, athletic frame. His arms were pulled up and outwards and tied to the headboard with thin twine, which was biting into the flesh of his wrists. His legs were splayed, feet apart. A clear plastic bag was moulded to his head, the features distorted underneath.

Erika always found naked corpses much more difficult to deal with. Death was undignified enough, without being exposed in this way. She resisted the urge to place the sheet over his lower body.

‘The victim is Dr Gregory Munro, forty-six years old,’ said Moss, as they stood around the bed. His brown eyes were wide open and surprisingly clear beneath the plastic, but his tongue was beginning to swell and poke through his teeth.

‘Doctor of what?’ asked Erika.

‘He’s the local GP. Owns and manages the Hilltop Medical Practice on Crofton Park Road,’ replied Moss. Erika looked over at Isaac, who was standing on the opposite side of the bed, examining the body.

‘Can you give me a cause of death?’ asked Erika. ‘I’m assuming asphyxiation, but…’

Isaac released the victim’s head, the chin coming to rest on the bare chest. ‘The evidence points to asphyxiation, but I’ll need to determine that the bag wasn’t placed over his head post-mortem.’

‘A sex game gone wrong? Autoasphyxiation?’ asked Moss.

‘Hypothetically, yes. But we can’t rule out foul play.’

‘Time of death?’ asked Erika, hopefully. She was now sweating profusely under her crime scene overalls.

‘Don’t push it,’ said Isaac. ‘I won’t be able to give you a time of death until I’ve had a closer look and opened him up. Extreme heat or cold slows putrefaction: in the case of the heat in this room, it’s drying out the body. You can see the flesh has started to discolour.’ He pointed to where the skin was blooming in shades of green around the abdomen. ‘This could indicate he has been here for a few days, but, as I say, I’ll need to perform the post-mortem.’

Erika cast her eye around the room. A long wardrobe of heavy wood lined the wall next to the door, and in the nook of the bay window there was a matching dresser with a mirror. To the left of the window was a tall set of drawers. Every surface was clear: there were no books or ornaments, or any of the general detritus that accumulates in a bedroom. It was very neat. Almost too neat.

‘Was he married?’ asked Erika.

‘Yes. The wife is no longer on the scene. They’ve been separated for a few months,’ said Moss.

‘It’s very tidy, for a newly single man,’ said Erika. ‘Unless the attacker cleaned up,’ she added.