‘I have a very good reason for this,’ she said, putting up her hands.

Twenty minutes later, Erika’s denim jacket was steaming lightly by the Aga and she was sitting with Marsh at the long, scrubbed-oak kitchen table. He’d pulled on a tracksuit, and his wife, Marcie, with her long dark hair on end and no make-up, was spooning tea leaves into a pot as the kettle boiled.

‘Jesus,’ said Marsh, after Erika had told him about Stephen Linley.

‘I’m sorry to have intruded on you both, but I’m just concerned about making calls to you from my mobile,’ said Erika.

‘Don’t you have a private mobile phone?’ asked Marsh.

‘No.’

‘What do you do when you want to make a private call?’

‘I don’t make many,’ said Erika. This hung in the air for a moment. The kettle came to the boil and Marcie poured water into the pot. ‘My point is,’ Erika continued, ‘that my phone call with Isaac will be evidence in our case, now he’s a suspect. But sir, he didn’t do this. I saw the crime scene. It was the Night Stalker, I’m sure of it.’

‘You said Stephen Linley had been bludgeoned over the head with an ashtray?’

‘It was the same type of plastic bag, a suicide bag; he was naked in bed. Something could have gone wrong, the killer could have panicked. He most likely fought back at her.’

‘You really think this is a woman?’ asked Marcie, incredulously.

‘Yes, we do,’ said Erika. Marcie came over and placed cups of tea down in front of them. Marsh’s phone rang on the table.

‘It’s Superintendent Nickson,’ said Marsh, looking at the screen before he answered.

‘He was at the scene with DCI Sparks,’ said Erika.

‘Hello? John, it’s Paul Marsh…’ He left the kitchen and closed the door behind him. Erika listened as his voice receded down the hallway. Marcie came and sat down opposite.

‘Would you like one?’ she asked, opening a tin of biscuits and placing it between them. ‘You look a bit pale.’

‘Thanks,’ said Erika. They each took one and chewed in silence.

‘I know what today is – the anniversary,’ said Marcie. ‘And I’m sorry. You know I’m sorry. It can’t be easy.’

‘Thanks,’ said Erika, taking another biscuit. ‘But I think tonight I sort of accepted it. Do you know what I mean? I still think about him all the time, but I sort of accepted that he’s never coming back.’

Marcie nodded. Erika thought how pretty she was without all the make-up she usually wore. It softened her.

‘Are you thinking of staying down south?’ asked Marcie, taking another biscuit and daintily dipping it in her tea.

‘I don’t know. The past two years have been like the first two years of my life again. First it was a day since Mark died, then it was a week, a month, a year…’

‘Planning anything is impossible,’ finished Marcie.

‘Yeah.’

‘Have you still got the house up north, in Ruskin Road?’

‘Yeah.’

‘That’s such a nice house, so cosy.’

‘I’ve never been back, since. I had a load of professional packers go in and put everything in storage. It’s rented out now,’ said Erika, ruefully taking another bite out of her biscuit.

‘You should sell up, Erika. You remember our house in Mountview Terrace? I saw online that it’s just been sold for five hundred thousand pounds! I knew the prices had gone up in Manchester, but that’s crazy. We sold it for three hundred thousand six years ago, when we moved down here. You could buy something in London. There are some lovely houses around Hilly Fields… And I saw a beautiful fixer-upper in Forest Hill…’

Erika strained to hear what Marsh was saying in the corridor.

‘Marcie, I didn’t come to talk about the price of houses,’ said Erika.

Marcie noticeably stiffened. ‘But you did come banging on our door at three o’clock in the morning. The least you can do is act politely.’

‘It’s been a long, horrible day, Marcie.’

‘Is every day a long day for you, Erika?’ Marcie said, standing and flinging the rest of her tea into the sink. It splattered up the tiles.

‘I’m sorry.’

‘No one else from Paul’s department thinks it's okay to come round and make inappropriate house calls in the middle of the night.’

‘This isn’t…’

‘What’s so special about you?’