David Ambrose's The Discrete Charm of Charlie Monk is a thriller with a difference. Charlie Monk is a genetically adjusted chimpanzee, raised in a laboratory and nurtured by virtual reality. As an assassin, he is unbeatably fast, technologically super-competent, and completely remorseless. But troubling flashes of a past that may or may not have been his start to invade his system, destroying discipline. Visual memory implants are the trickiest aspect of brainwashing.

‘He's James Bond to begin with, but nobody can be James Bond,' says Ambrose. ‘We go with the lie of the super-hero, but they don't exist, they're constructs of the imagination, so that's how I got into creating mine. I read a lot of physics, philosophy and psychology, and what I'm trying to do is ask metaphysical questions about consciousness, reality and identity within the form of the classic thriller. Where is the "I" in "me"? It doesn't exist in terms of brain function. Descartes's definition was abandoned long since. Nothing works at the moment.

‘Charlie Monk clings onto the idea of his humanity, but it may be a complete illusion. He may be a computer programme that thinks it's a real human being. And none of us can be more sure of who we are than Charlie.

‘At the end, I'm trying to mess with the reader's brain in a way that most thrillers don't. I tend to tell Frankenstein stories. Sod life-affirming! I've done that in Hollywood. I want them to say, "He writes mind-blowing books!"'

How close are we to producing a Charlie Monk? ‘I talked to geneticists who said, "Watch this space!" There's a huge amount of evidence that governments have been trying to create the totally obedient soldier. There was a psychiatrist working for the CIA out of a hospital in Canada, and he did the most appalling experiments on sick people using LSD and brain lesions. He didn't succeed in creating a Charlie Monk, but he killed a lot of people and drove a lot of others mad in the course of it.'

Was The Manchurian Candidate a big influence? ‘That's a good place to talk. It was one of the stories that always fascinated me. In fact, I worked with John Frankenheimer on The Year of the Gun. No, it wasn't very good. Most films aren't. And there's a good reason for it too.'

David Ambrose worked as a screenwriter in Hollywood for 12 years before turning back to his own writing. ‘I came to the conclusion that the only way to regard yourself as a screenwriter is to think of yourself as a secretary. Everybody has a right to have an opinion about your work except you. Couldn't Hamlet kill his uncle at the end of Act One? Pointless fighting it. You just say sod it. The novels are a way of getting my self-respect back. It's taken me almost 10 years to turn it around.'

Before Hollywood Ambrose wrote plays like Siege starring Alastair Sim, Stanley Holloway and Michael Bryant, and anticipates a revival of Abra Cadaver. What lured him into the movies was Orson Welles.

‘He was in Robert Siodmak's Battle for Rome; playing the Emperor Justinian in Romania and the script didn't work. I did three months rewriting on a daily basis. Everyone was scared shitless of him, so they sent the kid. I showed up at his hotel room and here was this enormous figure in a Mao suit, foot-long cigar, squinting at me. He told me he was on the wagon, poured me a tumbler of whisky, and proceeded to read through my scenes, grunting and puffing on his cigar. He said, "There's one problem. I can't play this. I'm what the French call ‘The King Actor' so I can't react to people. People have to react to me". So I had to go round to Laurence Harvey and the rest of the cast and say, Orson's going to have your line here. I got all the stick from their managers.

‘But Orson was great. We went to dinner in a black market restaurant in Bucharest, and fortunately he got fed up with sipping Perrier, doctor's orders, and fell off the wagon with a big thump. Thought he'd have a vodka and put a bottle away. We ended up living in a castle together. One thing I remember him saying was, "You're using ambiguity in the wrong way. You're using it as a smokescreen to hide behind because you don't know what you're saying. Ambiguity must be a scalpel". Such perception! I got a complete film course personally from Orson Welles'.