‘Did Andrea live with him?’

‘No. She lives at home with the parents, in Chiswick.’

‘That’s West London, yeah?’ asked Erika. Peterson nodded at her in the rear view mirror.

Moss went on, ‘You should see the family home. They’ve knocked four houses together, excavated the basement; must be worth millions.’

They passed a Topps Tiles, which looked closed, its car park a large empty square of fresh snow, then a Harvester Restaurant where a tall Christmas tree was being slowly fed into a chipper by a man wearing earmuffs. The drone of its engine vibrated through the car and then receded, as a cluster of run-down pubs rolled into view. In front of one called The Stag, an old woman with a sunken face leant against a peeling green door, smoking a cigarette. Beside her, a dog had its head in a bin bag, the snowy pavement strewn with old food.

‘So what the hell was Andrea Douglas-Brown doing around here, alone? Bit off the beaten track for the daughter of a millionaire who lives in Chiswick, isn’t it?’ asked Erika.

A flurry of snow briefly enveloped the car, and when it cleared, the Horniman Museum came into view. The sandstone edifice was flanked with tall yucca and palm trees, looking out of place caked in snow.

Moss slowed the car at the iron gates, pulling up beside a young male uniformed officer. Erika wound down the window and he leant down, placing a leather-gloved hand on the doorframe. Snow whirled into the car, sticking against the upholstered inside of the door. Erika showed him her ID.

‘Take the next left. It’s a steep hill. We’ve sent a gritter up there but take it slow,’ he said. Erika nodded and wound up the window. Moss took the left and they started up the steep road. As they approached the summit, a roadblock came into view, manned by another uniformed officer. Standing on the pavement to the left of the police tape was a group of journalists, rugged up in winter gear. They took interest in the police car’s arrival, and camera flashes bounced off the windscreen.

‘Bugger off,’ growled Moss as she attempted to change up to third. The gears crunched and the squad car lurched forward before stalling. ‘Shit!’ she cried, gripping the wheel. She slammed on the brake, but they continued to slide. Through the rear-view mirror Erika saw the road dropping away behind them. The photographers reacted to the drama and fired off more flashes.

‘Do a sharp left, now!’ shouted Peterson, quickly winding down his window and craning his neck round. Erika gripped the dashboard as Moss leaned into the wheel and managed to halt the slide, guiding the squad car into a recently vacated parking space by the kerb, which was free of snow. The wheels caught on the bare tarmac and they skidded to a stop in the parking space.

‘That was sheer luck,’ said Peterson with a dry grin. Snow was pouring in through his window and sticking to his short dreadlocks.

‘That was bloody sheer ice,’ said Moss, taking a deep breath.

Erika undid her belt, embarrassed to feel her legs shaking. They all exited the car as the photographers both jeered with laughter and called out questions about the identity of the dead body. Snow was rushing at them horizontally as they pulled out their ID, and the tape was lifted to let them pass. As Erika crossed underneath she took comfort in being back, the police tape being lifted for her, the feel of the ID in her hand again. Another uniformed officer directed them towards the iron gate leading into the museum grounds.

A huge white forensics tent now covered the boathouse, its base blurring into the mass of snow. One of the crime scene assistants was waiting with coveralls for Erika, Moss and Peterson, and they suited up before entering.

Floodlights inside the tent gleamed off the snow and illuminated the rotting wood of the low roof. They peered underneath, where three forensics officers were assisting the crime scene manager, combing over every inch of the inside. A rowing boat sat gleaming on the small wooden jetty, and a police diver, slick in his black gear, emerged from the icy water with a spray, bringing with him a warm, bilious smell of stale pond. Rubbish and murk floated around him where chunks of ice were melting under the glare of the lights.

‘DCI Foster,’ said a deep male voice. For once, Erika had to crane her head up to look at the tall figure that appeared from behind the boathouse. He pulled down his mask to reveal a proud, handsome face with large dark eyes. His eyebrows were heavily plucked, resulting in two immaculate lines.

‘I’m Isaac Strong, forensic pathologist,’ he said. ‘I know Moss and Peterson,’ he added. They both nodded. He led them round, past the outer wall of the boathouse, and they came to a metal stretcher placed lengthways against the back of the tent. The dead girl lay naked, save for the remnants of a torn and muddy dress bunched around her waist. Below were the torn strips of a black thong. Her full lips were slightly parted, and one of her front teeth was broken off, close to the gum. Her eyes were wide open in a milky death stare, and her long hair was matted with leaves and debris from the water.