The two police eyeball one another. ‘Professor Cullen, if you have a complaint to make about this person, you’ll need to come down to the station and we can deal with it there,’ DC Hassan says.

For a moment he thinks that this is just what he’ll do until a small voice inside stops him. Suppose this is a trap to lure him down to the cop shop so they can put him in a cell?

He clears his throat. ‘As I said, I have an appointment to get to.’

‘We won’t take any more of your time than we have to, then, sir. Just a few routine questions.’

‘Very well,’ he says, graciously, adjusting his position in the chair.

‘You mentioned earlier that Natasha might have had a drug problem?’ DC Worsley says, checking back her notes and reading carefully, ‘“The sort who might have to take something to steady herself, get through the day.”’

‘Yes, yes, you know, Valium or something like that.’

‘Did you know she was taking Valium? Did she disclose that to you?’

‘No, no, as I said, I didn’t really have much to do with her. It was more of a thought, really. A guess, you might say.’ He smiles. ‘Just trying to be as helpful as I can.’

‘We appreciate that,’ DC Worsley says. ‘There’s something else you can help us with. Do you remember what you were doing on Thursday, sir, the 3rd of April that would be?’

The day Natasha Tillotson went missing.

‘As I said, officers, Mark Ratner is the person you want to speak to. I’m pretty sure he was…’

‘We’ve spoken with Dr Ratner. He was in Thirsk on the 3rd and 4th attending an interview.’

‘Oh, well then, as I said, I can’t help you.’

‘We think you might be able to, sir,’ DC Worsley says. ‘We think you might be able to tell us why your car, a dark blue Volvo…’ she rattles off the licence plate number, ‘…the same car as is currently in the driveway, was caught on CCTV in the Three Lakes area at 9.23 p.m., very close to the time it’s estimated that Natasha allegedly committed suicide?’

‘Look,’ he says, ‘if this is about Nevis Smith…’

‘Why would it be about Nevis Smith?’

‘As I said, I am the subject of vindictive harassment from one of my students and her mother.’

‘If you want to make a complaint about that…’

Cullen cuts him off. ‘What exactly are you after?’

‘What might we be after, sir?’