The snow was melting when Moss and Kay arrived at Coniston Road, and they tried Don Walpole’s front door. Kay was ready with the portable DNA kit, but there was no answer.

‘Shit,’ said Moss. She pulled out her radio, and called into the station. ‘Crane, I need you to do a search for Don Walpole…’ Moss looked up and saw the old man in his usual spot, smoking a cigarette. ‘Hang on, I need to call you back.’

They came out of the front gate and went over to the old man.

‘You looking for Don?’

‘Yes, we are,’ said Moss, showing him her warrant card. ‘My colleague said that you saw him and his wife leaving yesterday afternoon. Have you seen them today?’

The man shook his head. ‘I’m out here a lot; the wife don’t let me smoke indoors. I was out just before six and again at seven-thirty and eight… And again at nine.’

‘So, you’re quite a heavy smoker?’ asked Kay.

‘You will go far as a detective,’ he said, pointing his cigarette at her and grinning with a set of yellow teeth.

‘You didn’t see any lights on, any movement?’ asked Moss.

‘Nope.’

They came back to the car and Moss called back in to Crane at the station, telling him to keep trying Don’s phone and to put out a search on his number plate against the national database. They then drove the short way around the corner to David and Elspeth Pitkin’s house.

David Pitkin opened the door; he was dressed in black, and had deep, dark circles under his eyes. They showed their ID and asked if they could come inside to talk.

‘Haven’t you people done enough?’ he said imperiously.

‘We have some more questions about Joseph, about his friendship with Marissa Lewis,’ said Moss, trying to be tactful.

‘I’m sorry, no. My wife is in a terrible state. She hasn’t left her bed since…’

‘I’m so sorry about what happened to your son,’ said Kay. ‘We just don’t want his death to be in vain. We think he may have known things about this case. He may have been able to help us with our investigations.’

David looked down at them from the step, chewing over what they were saying. ‘Where is she?’

‘Who?’ asked Moss.

‘That bloody awful detective with the blonde hair.’

‘She is on leave. I have taken over the case,’ said Moss.

‘Is this because of my formal complaint? I wrote to the assistant commissioner, asking for a full enquiry and that she be removed from duty.’

‘Yes, that’s in process. That’s why I am now on the case,’ said Moss. She was sure Erika would understand her playing along with David Pitkin.

He took them through to the kitchen. ‘Would you like tea?’

Kay looked at Moss for guidance.

‘We wouldn’t want to impose,’ said Moss. ‘We just need to ask you a few questions.’

‘Have some bloody tea!’ he snapped. ‘I need to keep busy.’

They nodded and sat at the long table. Moss noticed that all the clocks, of which there were many on the walls, had stopped at 1.25 p.m. The room was silent.

‘It’s something I wanted to do,’ he said, noting her gaze. ‘That’s the time the doctor pronounced Joseph…’ He didn’t finish the sentence. They waited in silence as he made three cups of tea and then came to join them.

‘How long had Joseph been involved in photography?’ asked Moss. David Pitkin looked surprised at the question.

‘I don’t know, four or five years.’

‘And you bought him supplies?’

‘At school, his art teacher did a project where students made a pinhole camera out of lavatory rolls, tinfoil and photo paper. He found it fascinating, and pestered me to buy supplies so he could make his own pinhole camera.’

‘And he needed a dark room to process the photos?’

‘Yes.’

‘Where did you buy the chemicals?’

‘I got them locally from a camera shop in Greenwich. Detectives, I’m not sure how relevant this line of questioning is, unless you are planning to start doing photography as a hobby?’

‘We are trying to establish where Joseph went in connection with his hobby.’

‘It’s wasn’t a hobby. He wanted to do it as a career.’

‘When did Joseph graduate to having his own camera, buying his own materials?’

‘I don’t know. As I said, a few years. I was still practising as a barrister back then and I rather neglected my home life. I wouldn’t see my family for days on end…’ David looked wistfully out of the window and sipped his tea. ‘Makes me think it wasn’t all worth it, my job. The law… It’s just a huge chess game.’

Moss didn’t press him.

‘Was Joseph a member of any camera or photography clubs?’

‘Again. I don’t know.’

‘Could we speak to your wife?’ asked Kay.

‘No, you may not. The doctor had to come early this morning to give her something to sleep.’

‘Did Joseph get paid for any of his photos?’

David gave a bemused smile.

‘No. He was signing on, for a long period. You must know this, officers.’

‘Did Marissa Lewis ever come to your house?’ said Moss. ‘I’m asking in particular about the past year?’

‘No. Not that I know of. We were always rather worried about him; he never seemed to have any interest in either sex.’

Moss looked at Kay. They had exhausted all of their questions, and there was just one other thing they had to ask about.

‘Mr Pitkin. I need to show you some photos we found on Joseph’s mobile phone. They may be upsetting, but I only ask you to look at them because they are vital to our investigation.’

David’s eyes narrowed as Moss pulled out a cardboard file. She opened it on the table and took out the photos of Joseph tied up in the restraints. She also took out the note with the gas mask drawing.

David looked through the photos, attempting to stop his emotions from showing. Finally, he looked up, and his eyes were full of anger.

‘Who the hell do you think you are, to come into my house and show me these?’

‘Mr Pitkin. Did Joseph ever mention a friend, or that he was scared for his life?’

‘Did anyone mention to you that Joseph looked at risk of taking his own life?’ he shot back.

‘No.’

‘But you must have seen that he was distressed when he was being interviewed? Did no one at your station think to call a doctor, or think that he shouldn’t have been put back in that cell, BY HIMSELF!?’ David swept the photos off the table. ‘NOW GET OUT OF MY HOUSE!’

Kay hurriedly picked up the photos from the floor and stuffed them back in the file.

‘Mr Pitkin, please, do you have any idea who might have sent Joseph a note like this?’

‘DID YOU HEAR ME?’ he bellowed. He grabbed Moss by the back of her coat and dragged her up out of her chair and into the hallway.

‘Sir. Please, stop this,’ said Kay, moving after them as David dragged Moss to the front door.

David let go of Moss, leaned across, turned the handle and pulled it open. Moss put up her hand when he tried to grab her again.

‘That’s enough,’ she said, stepping outside. Kay was no sooner out of the door behind her than it was slammed shut. They walked out onto the pavement.

‘You okay, ma’am?’

‘Yes, and please don’t call me “ma’am”. I’m not a member of the royal family,’ said Moss. She straightened her jumper under her jacket. ‘What else were we expecting? I just thought it was worth a shot, in case he knew something.’

‘Do you think he knows anything?’ asked Kay.

‘No, I don’t. But I’m not much good with my gut instinct. That’s Erika’s speciality.’