For its title sequence, The Full Monty (15) resurrects a Seventies promo film for Sheffield, a showreel that may have influenced the aesthetic Weltanschauung of a young Jarvis Cocker. It's new-town retro with a hint of Soviet optimism. Tower blocks gleam in the sun, buses cruise around new concrete roundabouts, molten steel bubbles in crucibles. A smoothly cheerful voiceover that might once have been used to advertise Dralon Zed beds enumerates the city's industrial triumphs. Then the screen blacks out with the caption, "25 years later". We're in the present day, and civic modernism has been discredited by the heritage pub, stone cladding, and the fact that Marxism is dead as Adorno. In The Full Monty's Sheffield the working man is an oxymoron. The only way male dignity can be re- invented is for blokes to get their kits off and wave their todgers in the air.

The hero of Peter Cattaneo's film is Gaz (Robert Carlyle), a redundant steelworker whose ex-wife Mandy (Emily Woof) has moved to a new faux- Georgian estate with their nine-year-old son. Gaz's mates are similarly undermined: Dave (Mark Addy) is struggling with impotence, and fears that his wife (Lesley Sharp) will run off with one of her fit young colleagues at Asda. Ex-foreman Gerald (Tom Wilkinson) doesn't even have the balls to tell his wife he's lost his job.

Cattaneo doesn't attempt the mildewed detail of Ken Loach, nor the scattergun satire of Brassed Off, a film with which The Full Monty has much else in common. Instead, he uses broad comedy to make post-industrial deprivation a gender issue, fleshing out the problems of millennial urban masculinity. Sitting forlorn in the JobClub, Gaz assesses the current status of his sex: "We're mutations ... We're not needed any more."

And as far as Simon Beaufoy's script is concerned, he's right. The women of Sheffield have occupied the roles that redundancy has forced their menfolk to vacate. They have jobs, they spend their hard-earned money on striptease nights at the local working men's club. Once there, they use the gents, and they even piss standing up.

Gaz, Dave and Gerald recover their self-esteem by recourse to a traditionally female way out of the poverty trap - they sell their bodies, or at least the spectacle of their bodies. And The Full Monty may be the first film to deal directly with men's relationships to their bodies. It is certainly the first film in which a big hairy bloke strips to "Je t'aime". Dave confronts his anxieties about his weight; Gerald worries about getting overexcited during the show. Guy (Hugo Speer) nearly breaks his neck at the audition while trying to do a Donald O'Connor back-flip, but he's too well-hung to reject; Horse (Paul Barber) is recruited partly because the others assume that his blackness guarantees a crowd-pleasingly large packet. (In fact, we later see him making a desperately dissatisfied phone call to the suppliers of a penis-enlarging kit.)

Each character undergoes a subtle transformation between rehearsal and performance: Dave gets back his pride, Gerald loses his snobbery, Guy and pigeon-chested security guard Lomper (Paul Huison) discover they're in love. Emotional and physical nakedness are negotiated with equal sensitivity.

Cattaneo yields a tremendous sentimental energy from these events, and handles it well enough to keep his film coherent. Moreover, Beaufoy's script provides him with a cluster of uproarious set-pieces - the men bumping and grinding to Donna Summer's "Hot Stuff" at the DSS; the men watching Flashdance for inspiration, Dave complaining that there's too much acetylene in Jennifer Beals's pop-video blowtorch. This perfectly judged moment has powerful resonance - steelworkers on the scrapheap, watching a now-faded Eighties dance star playing at being a steelworker as they attempt to mimic her dizzying moves.

There's more zeitgeist on offer in Richard Donner's erratically thrilling thriller Conspiracy Theory (15), and this may make it the film of the decade. Not in the sense that it represents the finest cinematic work of the 1990s (which it certainly doesn't), but because it's a consummate fin-de-siecle document, and - like The Full Monty - is particularly engaged with the special problems of late-20th-century manhood. It might, however, express more than it realises: as its X-phile hero Jerry Fletcher (Mel Gibson) says, "I don't know what I know, but I know it's big."

Taxi-driver Jerry is an unstable loner obsessed with wild theories about black helicopters, grassy knolls and the secret pact between Oliver Stone and George Bush. He takes his conjectures to Alice Sutton (Julia Roberts), one of those dedicated-but-troubled female lawyers who 10 years ago would have been played by Cher. Between them, they discover that Jerry is actually part of a monstrous secret government plot co-ordinated by the sinister Dr Jonas (Patrick Stewart), a plot that progresses with a smart pace and a keen sense of contemporary angst, before coming asunder in the final reel.

Gibson does Jerry as Travis Bickle Lite, pepped up with a free-associating patois borrowed from David Helfgott. The urgency of his acting reflects the mid-life career crisis that has struck the fortysomething Australian star. Now Hollywood has George Clooney, Mel's days as a light romantic lead are probably numbered. In response to this perhaps, Richard Donner's camera treats him like a proper actor: shorn of his dreadful Lethal Weapon blow-dried mullet, he performs as if his life depended on it. While Donner is careful to flatter Julia Roberts by lending her as much gentle luminosity as he can muster, her co-star is allowed to look his age. When Patrick Stewart straps him into a wheelchair, tapes his eyelids and shines a blinding light in his face, the housewives' heart-throb looks pretty ghastly, as pasty and pop-eyed as Liza Minnelli on a bad-mascara day.

And here's another departure from regular heroic territory. Jerry is a classic hysteric in a textbook Freudian sense - he's a man suffering from memories that translate into physical ticks and seizures. Just to make sure we get the point, Brian Helgeland's script goes to the trouble of literalising Jerry's Id, as a basement room decorated with pictograms relating the traumatic experiences to which his conscious mind has no access. It's left to Roberts - as much his analyst as his lawyer - to piece together the fractured pieces of his story, and help him to his own talking cure.

The plot pitches Freudian paradigms at its audience like Jerry hurls theories about Vatican and CIA corruption at his hapless passengers. Noseying round her apartment, Jerry hypothesises that Alice jogs on her treadmill with her back to her father's photograph because she can't face the consequences of his death. This seems like a direct encouragement to the audience to get thinking in such terms. But when it comes to reading the film's own subconscious, there's nothing doing but ambiguity and confusion.

Helgeland's script suggests that Jerry's compulsion to produce far-fetched theories is a neurotic displacement. He is repressing memories of his involvement in a real government cover-up, and jabbering about the space shuttle being a covert seismic weapon precisely because he's unable to dredge the experience of Patrick Stewart's Manchurian Candidate-style experiments from his head. Rather clever, really.

But the film leaves Jerry's hypotheses only half-digested. It's unable to decide where paranoia ends and justifiable suspicion begins. A news report seems to confirm that the shuttle is responsible for major earthquakes, and events seem to verify Jerry's claim that American society is covertly ruled by a powerful group of families. It's an appropriate schism, perhaps, in a film so steeped in contemporary anxiety. But where does that leave Oliver Stone and George Bush? If you know, you're probably Brian Helgeland. If you don't, maybe you have your suspicions.

Cinema details: Going Out, page 14.