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Ransom Ron Howard (15) Extreme Measures Michael Apted (15) Carla's Song Ken Loach (15) Quadrophenia Franc Roddam (15)

Imagine that Mel Gibson could be convincing in a film that didn't even require him to throw a single punch until the last five minutes. Then imagine that that film was a thriller directed by Hollywood golden boy Ron Howard (Apollo 13, Parenthood). Then - and here's the hard part - imagine that it turned out to be a cruel and intense examination of apparently stable relationships fracturing under pressure. Yes, I know it sounds far-fetched, but it's true: Ransom is the first Ron Howard movie to haunt rather than desert the mind after the credits have rolled, and the first one to pose no major threats to diabetics.

Tom Mullen (Gibson) is an airline tycoon whose young son is kidnapped, and a ransom of $2m demanded. The FBI moves into Tom's penthouse and engineers a plot to sabotage the kidnappers during the ransom drop. But when it goes horribly wrong, Tom instigates a potentially dangerous plan of his own, appearing on television to offer the $2m as a reward for the return of his son.

The final 20 minutes change this tangy character study into a revenge thriller, a transformation that is temporarily gratifying and yet ultimately diminishes some of the film's coiled emotional power. Until then, it's pleasingly unpredictable. Gibson manages to walk a tightrope between being vulnerable and volatile, but the film's ambiguities provide the real surprises. As you'd expect from any screenplay that the Clockers author, Richard Price, had a hand in, the distinction between good and bad is fuzzy, to say the least. The film even manages to find sympathy with the kidnappers, intercutting shots of the boy's mother (Rene Russo) with corresponding close-ups of a harassed female captor so that these real and temporary guardians become almost interchangeable, and the opposing parties - the abductors and the family - are momentarily united in their anguish. That kind of objectivity is a rare and lethal weapon in Hollywood film-making; when it surfaces, you can feel like you're witnessing an act of insurrection.

Hospitals have always been a source of horror and suspense, and I'm not talking about the NHS. Film-makers realised a long time ago that the antiseptic corridors and euphemistic jargon were a breeding ground for distress and paranoia. Extreme Measures is more Coma than The Kingdom, it's tense but not greatly unsettling, though it's paced with immense skill. You may even find yourself watching open-mouthed from behind your hands, either in fear at what you're seeing, or stupefaction at plot-holes that are badly in need of stitches.

The film opens magnificently, with two naked men bursting from a New York basement, burped out into the night like two obese babies. They clutch on to each other, swaddling themselves in sheets of plastic stolen from scaffolding, and gibbering as though they've escaped midway through a lobotomy. That's not far from the truth, as Dr Guy Luthan (Hugh Grant) discovers when he treats one of the men and discovers irregularities in his heartbeat and hospital records.

When colleagues become flustered by this snooping, Guy knows he's on to something. Bizarrely, his hunt for the truth leads him to a group of underground nomads - the ethnically balanced Molepeople, who appear to live a far more harmonious life then their street-level counterparts, apart from the annoying problem of occasionally being kidnapped and experimented on by the sinister Dr Myrick (Gene Hackman). Shades of early Cronenberg prevail (acknowledged by a cameo from the controversial Canadian), and director Michael Apted takes the dark themes seriously enough to distract from the script's minor misjudgements, such as christening a pair of FBI agents Burke and Hare.

Carla's Song combines some of the most truthful, touching work that Ken Loach has done with a final hour of such numbing banality that you can scarcely believe it is part of the same piece. Robert Carlyle is fierce and touching as George, a Glaswegian bus-driver who meets Carla (Oyanka Cabezas) when he defends her from a ticket inspector after she tries to ride his bus without paying. George is hooked. He trails the enigmatic Nicaraguan around Glasgow, finds her a new flat, and temporarily hijacks a double-decker to take her on a picnic. But Carla has some serious problems, indicated by the scars on her body, and on her memory. George's - and the film's - troubles start when he accompanies Carla back to Nicaragua and encourages her to face the secrets in her past instead of fleeing them.

All the precious chemistry between Carlyle and Cabezas is squandered once the picture leaves Glasgow, and Loach and screenwriter Paul Laverty attempt to sate us with a hasty sketch of late-Eighties Nicaragua. There are many bad things about this second half, like the all-singin', all- dancin' Sandinistas, who serve the same ahh-look-at-the-natives function as the American-Indians did in Dances with Wolves. Most painful is the actor Scott Glenn, who has never been worse. He's called upon to deliver the film's climactic revelation but gives it all the impact of a Christmas cracker joke. For a more lucid picture of Nicaragua's history, read Salman Rushdie's The Jaguar Smile. And if you want to cling on to your memory of how good Loach can be, leave Carla's Song after the first hour.

As one Who-based musical ends its run in the West End, another begins. But Quadrophenia couldn't be more different from Tommy - it is grounded in a salty reality where messianic folk heroes end up in nine-to-fives like those who worship them. The other difference from Tommy? The music is awful. But the movie is saved by a feral performance from Phil Daniels, which needs to be seen by anyone young enough to be labouring under the misapprehension that the peak of his career was singing with Blur.

He plays Jimmy, a Jack-the-lad immersed in the Mod lifestyle until he begins to question his friends, and his life, and sees his dreams crushed along with his Lambretta. Almost two decades after its original release, the film still feels urgent. The only irrevocable damage that the intervening years have wrought is revealed in the casting of a minor but pivotal part: was 1979 really so long ago that audiences could accept the preposterous notion of Sting playing a guru of cool? Such innocent times

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