‘Erika, help me, he’s dead!’ came a voice she barely recognised.

‘Isaac, is that you?’

‘Yes! Erika, you have to help me. It’s Stephen… I just came to his flat, and found him… Oh God… There’s blood, there’s blood everywhere…’

‘Have you called the police?’ asked Erika.

‘No, I didn’t know who else to call… He’s lying on the bed, he’s naked…’

‘Isaac, listen, you have to call 999.’

‘Erika… He’s dead and he has a plastic bag over his head…’

The rain was torrential when Erika arrived at the Bowery Lane Estate. As her windscreen wipers worked to clear the deluge, the blue lights from the police cars crowding the entrance seemed to mix with the water in streaks. She parked behind one of the large support vans and climbed out into the lashing rain.

‘Ma’am, move your car, you cannot park there!’ shouted a uniformed officer running towards her. She pulled out her ID.

‘I’m DCI Foster, I’m responding to the call-out,’ she lied.

‘Are you the Senior Investigating Officer on this?’ asked the officer, putting a hand up to shield his eyes from the rain. It crackled as it landed on the waterproof covering on his helmet.

‘I’ll know more when I see the scene,’ she said. He waved her past him. She walked towards the police cordon. Police cars were parked up on the pavement, and an ambulance had pulled into the courtyard on the grass, its lights adding to the symphony of blue and red that played across the block of flats.

Erika looked up and noted that lights were coming on in the windows. A uniformed officer was yelling for people to go back inside, and Erika saw a group of young girls in their pyjamas being herded in by their mother.

She showed her ID at the police tape.

‘You’re not on the list,’ the uniformed officer shouted above the noise of rain and police sirens.

‘I’m in the first response team. DCI Foster,’ she shouted, brandishing her ID again. He nodded, she signed his clipboard and he lifted the tape for her.

A large glass door was propped open and she went through to a stark stairwell. The concrete was grey and mottled with years of stains. When she reached Stephen Linley’s flat, it was crowded. She flashed her ID and was given a suit, mask and shoe covers, which she quickly pulled on in the corridor. When she went inside, every available space in the small flat was being dusted for prints, and photographed. The crime scene officers worked silently and paid her no attention as she climbed the spiral staircase with a sense of dread. She could hear soft murmurings coming from above, and the click and squeal of the crime scene photographer’s camera.

The bedroom was worse than she’d imagined. A naked man lay on a white mattress, which was saturated with blood. His body was fairly unmarked but his head was unrecognisable inside a plastic bag. The white wall behind was streaked in red. The room was filled with officers – one in particular stood out to Erika because of his tall frame. Beside him was a much shorter, fatter officer who had one of the drawers open in a large dresser and was pulling out a selection of dildos, leather harnesses and what looked like fetish hoods. He held one of the black PVC hoods up.

‘Looks like a fetish breath control device,’ he said.

‘Jesus, no wonder he came a cropper,’ said the tall officer. Erika’s heart sank when she realised who the voice belonged to.

‘DCI Foster, what are you doing here?’ said DCI Sparks.

The large man beside him placed the hood in an evidence bag with his gloved hands, then turned. His eyebrows were long and bristly above craggy eyes.

‘I… I received a call,’ she said.

‘From who? The first response were City of London Police. They called my team in,’ said Sparks. ‘This is Superintendent Nickson.’

Both Sparks and Nickson stared at her from behind their masks. The camera fired off two blinding flashes.

‘You’re a long way from home, don’t you think?’ added Nickson. He had a gruff, no-nonsense voice.

‘I’m… er…. I got a call from the forensic pathologist, Isaac Strong,’ Erika said, shakily.

‘I’m the forensic pathologist, Duncan Masters,’ said a small man with intense eyes, working in the corner. ‘Dr Strong is being interviewed by uniformed officers. He’s not here in a professional capacity.’

‘Hello, Dr Masters,’ said Erika. ‘I’ve been working on the double murder asphyxiation of Jack Hart and Gregory Munro. I’m here also in a professional capacity. I believe that this murder could have been committed by the same person.’