This has to be the Doctor Who effect: you wait ages for the BBC to produce a science fiction programme and then two come along at once. As well as Hyperdrive, a Red Dwarf-aping sitcom, they are also currently showing Life On Mars, a genre spin on the format that's the bread and butter of networks the world over: the police procedural. It's safe to say, though, that Doctor Who never contained the phrase "I don't give a tart's furry cup."

DI Sam Tyler (John Simm) is investigating a kidnapping in present-day Manchester when he is knocked down by a car. Something very strange happens. When he comes to he's still a copper and his name is the same, but his rank and everything else have changed. As he helpfully puts it in the voiceover at the beginning of each episode:

"I had an accident and I woke up in 1973. Am I mad, in a coma, or back in time?"

No answer is immediately forthcoming, but the question becomes increasingly important as the show progresses. Having weathered the baffling transition back to a time when he was five, Tyler's biggest problem is his new superior officer, DCI Gene Hunt (Philip Glenister). Hunt is an unreconstructed Northerner and dinosaur copper who has not yet been usurped by nimbler mammals like Tyler. As you might expect, they are a comically mismatched couple who come to blows almost immediately upon meeting. This sets the tone for a working environment which seems more like a classroom when the teacher has popped out, and can often be very funny. When the lads in the station are having a kickabout with a football outside Hunt's office he becomes irate, not because of their behaviour, but because it almost knocks a beloved poster off the wall: "Gary Cooper almost come down!" He tells them to go and play in the hall.

This schoolyard atmosphere permeates even the most serious investigations and the show revels in it. There is also undoubtedly an element of affectionate television nostalgia for The Sweeney. (Readers who have never seen The Sweeney might be interested to see what Inspector Morse did before he moved to Oxford.) However, pleasurable as it to watch Simm and Glenister sparring, some of the cheap slapstick is desperately at odds with the tone elsewhere. In the popular imagination the mid-Seventies in Britain were the pinnacle of police corruption, exemplified by the behaviour of the West Midlands Serious Crime Squad. Tyler is naturally horrified by the practices he encounters, but the writers engineer plenty of highly contrived scenes to make sure that both the pros and cons of Seventies policing are carefully displayed. This makes the viewer hard-pressed but to have some grudging sympathy for the monstrous attitudes on display. For some viewers the word "grudging" will be entirely absent. In fact, a columnist for The Sun, Britain's bestselling and stupidest newspaper, opined after the second episode that "what Life On Mars shows is that combining old-fashioned policing with today's technological advances is the way forward."

At first Tyler is completely at sea in a world without modern forensic science. Even more basic forensic measures are shunned by Hunt, for whom crimes don't "get solved in the lab." Instead Tyler falls back on evidence-gathering fundamentals and psychological insight. This isn't something that the old school cops have much time for; WPC Annie Cartwright (Liz White)—the obligatory love interest/token female character—has a degree in the subject, but is relegated to cleaning vomit out of the cells owing to the gender roles of the time. Eventually though, Hunt comes to accept that Tyler's methods have some validity and the time-traveler is soon using them to solve the Crime Of The Week.

So back to the rhetorical question Tyler poses himself. To begin with it is strongly suggested that this isn't really science fiction at all, and if it is a genre work it is so in the same way that Iain Banks's The Bridge is: a slipstream coma dream that can be read as either fantastic or naturalistic. For instance, the sounds of a hospital intrude, and Tyler hears the voice of a doctor talking to him. Later, the writers bring out an old classic and he decides to "walk till I can't make any more detail," hoping that he will run up against the limit of his brain's processing power and that his hallucination will disintegrate. Again though, the writers want to have their cake and eat it. Just as with the crime plots that give each episode its background, misdirection is the order of the day here. For every clue the writers give the viewer, they offer a contradictory one. The hoops they have to jump through to maintain this ambiguity often seem forced and neither are they really able to integrate all the disparate elements. Instead they are reduced to flashing hints that there is more to it than meets the eye. Who is the girl in the red coat running through the woods? How is she related to the sinister girl from the television test card who has taken to haunting Tyler?

The show might build something interesting out of these disparate aspects, but at the moment Life on Mars remains diverting but unexceptional entertainment. Let's just hope things are wrapped up by the final episode. British TV shows, with their short runs, are usually quite good at having proper endings. At a time when the producers of Lost openly boast that they have no intention of providing a satisfactory conclusion, that would be something to prize.

Martin Lewis lives in East London. His reviews have appeared in Vector, The SF Site, The Alien Online, and Interzone. In this bio he tried to strike a balance between being too cute and being too boring. He failed.