IN Different for Girls (15), motorcycle dispatch rider Prentice (Rupert Graves) runs into an old schoolfriend and finds that he's not the man he was. Karl, once a nervous public schoolboy, has become Kim (Steven Mackintosh), a smartly dressed post-operative transsexual.

Written by acclaimed television writer Tony Marchant, Richard Spence's film bravely attempts to deal with a subject that cinema has rarely taken seriously. There's a refreshing lack of cheap sexual innuendo, and the plot produces a happy ending with satisfying predictability. It's just a pity that the film itself suffers from an identity crisis that makes Kim's gender-switch seem rather uncomplicated: it knows in its heart that it was destined to be TV drama, to run for a couple of consecutive Sundays on BBC1. And if you need proof that you really shouldn't have to pay to watch it on a massive screen that its images don't suit, look no further than Spence's unimaginative directorial technique, which mainly consists of pointing the camera at whoever's talking.

But as well as living a lie, the film is in desperate need of a rewrite. Some of Marchant's dialogue is horrible ("My heinous penis, my wrong schlong!" declaims Prentice in a moment of rage) and its insults are particularly corny: in the opening flashback to the fifth-form showers, Karl is taunted by his classmates with the word "eunuch" (which isn't what we would have said at my school). And in one of several thinly written tirades that Marchant forces upon Graves, the actor is made to shout "You sad bunch of chromosomes!" at his fellow dispatch riders. No, they didn't seem too impressed, either.

The best work in this odd little movie is by Steven Mackintosh (recently seen as John Harmon in the BBC's Our Mutual Friend). His task is one of the most challenging any actor could wish for: playing a man who's had his genitals remodelled, and who's taking a course of female hormones - without actually doing these things himself. His narrow, sleepless-looking eyes weren't made for mascara, but in certain lights, he does look a little like Juliet Stevenson. His subtle, thoughtful and meticulous performance is persuasive enough to dispel any air of drag-queenery, and gets you thinking about some of the issues raised by transsexuality itself. Big issues like, what is gender, exactly? Is it a state of mind or a biological fact?

But ultimately - and disappointingly - Different for Girls remains perplexed. It seems to argue that femininity means eating chips with your pinky finger sticking out, having a predilection for angora cardigans and excessive tidiness, and doing your shopping at Marks & Spencer. Masculinity, on the other hand, is having a penchant for big motorbikes, the Buzzcocks and lager. For the purposes of comedy, Spence and Marchant make both look equally daft. They bring on girly sing-songing seccies and hairy-arsed bikers to point up the absurdity of gender stereotypes, and they cast a few gender- ambiguous extras (there's a woman with a jawline like Roger Ramjet standing in the background of Kim's office) to suggest that there's more to being male or female than meets the eye. They even draft in Miriam Margolyes to do her butch Mother Superior act as Kim's firm-but-fair boss.

The problem with satirising gender to this extent is that it makes its heroine's attachment to being female look like affectation rather than self-determination. Which makes Different for Girls an amusing but confusing experience. Steven Mackintosh's performance was so good, however, I cheered her on just the same.

On a trip to Norway last year, I'm sure I didn't meet anyone who wasn't eight-foot tall and blond. One of the achievements, therefore, of Pal Sletaune's Oslo-set black comedy, Junk Mail (15), is that the director has managed to assemble such a fantastically ugly cast. They're as red- eyed and daylight-starved as film critics. The pasty-faced, hang-dog Robert Skjaerstad plays Roy, a postman who subsists on cold tinned spaghetti and scrubs his armpits with washing-up liquid. His professional ethics are just as filthy: he steals mail, dumps bundles of letters, and commits acts of misconduct that would bring a wrinkle of disgust to the smooth Plasticine nose of Postman Pat. By the time, however, he is sneaking into a flat belonging to Line (Andrine Saether), the deaf laundromat worker with whom he's fallen in love, and munching his way through her discarded bowl of soggy Frosties, you begin to admire his unerring sense of perversity. And Sletaune's, for that matter. Shot in institutional greys and greens, his film goes for tenderness and dank scuzz with equal enthusiasm. And though its scenes take place in seedy flats, insanitary public toilets, second-hand mucky bookshops and greasy spoons from which even Roy won't eat the stale teacake, there's human warmth radiating from under the grime.

Guy Maddin's Twilight of the Ice Nymphs (no cert) transports its audience to Mandragora, a faery kingdom where the sun never sets and where none of the dialogue makes much sense. "You can hear the mice wrestling down the bog," says the hero, clutching a baby goat under his arm. Peter Glahn (played by an actor giving a performance so bad he has removed his name from the credits) is a political prisoner who returns home to find that his ostrich-farming sister (Shelley Duvall, goofily wacko as ever) has fallen hopelessly in love with a one-legged mesmerist (RH Thomson, in a part for which Dudley Moore's Mr Spiggot would have been perfect). The talk is all faux-naif stuff about fecundity and bull's pizzles, but this doesn't faze the cast. It doesn't faze even Thomson, who has to explain that his companion Juliana (Pascale Bussieres) was born after a twisted scientist impregnated a "hardened prostitute" (whatever that is) with the sperm of a murderer who ejaculated on the gallows as his windpipe snapped. The production design is a camp riot of Cellophane, chiffon taffeta, gauze and sequins, and anyone who's a bugger for a baroque spandrel studded with gold pelicans will doubtless faint with pleasure. It was like rummaging around in Barbara Cartland's knicker drawer, but without the thrill of imminent discovery.

Cinema details: Going Out, page 10.