TELEVISION / DIY thriller killer

IF YOU'VE ever dreamt of writing a 'major two-part thriller' (the words are those of the Channel 4 press office) you could do worse than watch some of Tony Bicat's Exchange of Fire. I say 'some' because you're not being paid to sit through until the credits roll (and frankly, I'm not paid enough); in any case, the important lessons will be absorbed relatively quickly.

Lesson One is: Don't be nervous. You may have assumed that this level of expenditure on a piece of television would require the writer to come up with a complex and plausible plot. Not necessarily credible, you understand - most thrillers deal to a certain degree in fantasy - but merely plausible, sufficiently sanded-down to prevent your higher reasoning snagging on jagged edges. This obviously isn't the case. Exchange builds its plot on the following jerry-built foundations.

You are asked to believe: that a Havel-style Czech Prime Minister would send his 17-year-old daughter on a hearts-and-minds mission to London; that despite threats to her safety she stays in a grubby hotel rather than the secure and lavish embassy; that she bears a strong physical resemblance to the daughter of a libertarian philosopher who has supported Czech dissidents; that she visits said philosopher in hospital at exactly the same time as said daughter and - you had better swallow what you've got in your mouth already, otherwise you're going to choke - that the girls are wearing virtually identical clothing, down to a fetching grey beret.

Lesson Two is: I really mean it. Don't be nervous. You assume that if the plot is nonsense, then the dialogue must be pretty special. Not so. The Prime Minister's daughter explains at one point that she learnt most of her English from American videos, which at least gives her an alibi. On the same principle, the older characters appear to have belonged to a Prague film club with an obsessive interest in Forties B-movies. 'You know . . . (soulful pause) I always loved you', 'There is no us' / 'Look me in the eyes and say that', 'So far our brave little country has had little from England but fine words', 'Take her out of herself, she thinks too much' - all the old favourites are there.

Lesson Three is: Be utterly shameless. Don't worry if your story includes beat coppers who happen to be armed and MI5 men who conduct their surveillance by standing at uncurtained windows with an array of equipment like a Dixon's display cabinet. Don't worry if the production bulges with fake misunderstandings, clumsy continuity, inconsistency of characterisation and an almost criminal disregard for the intelligence of the viewer. Somebody, somewhere might make your film.

The medical term for the trauma a film like this inflicts is 'gross insult to the brain'. It normally results in unconsciousness but don't take any consolation from that - even if you were in a coma I suspect Exchange of Fire might provoke you to yelps of outrage.