John Sayles is generally regarded as the most consistently impressive of American independents - from his wonderfully knowing monster movie scripts for Corman (Alligator, Piranha), to directing such formidable movie feasts as the baseball scandal movie Eight Men Out, the brilliant union western Matewan, and the film that single-handedly created the thirtysomething generation, Return of the Secaucus Seven. Arguably the most openly left-wing of US film-makers, his last, City of Hope, stands as one of the key films of the 90s so far - an elaborate, coruscating and stylish examination of inner-city tension and political corruption. Passion Fish, therefore, is a major change of degree.

As the film opens, daytime soap queen May-Alice (Mary McDonnell) lays paralysed in hospital, the victim of a bizarre car accident in a New York street on her way to get her legs waxed (Sayles is never anything if not wryly ironic), and in a fit of self-pity she moves back to her family home in the Louisiana bayou. Embittered by circumstance and drinking heavily, she goes through a string of live-in nurses before the agency sends her the black Chantelle (Alfre Woodard), a former drug-addict Chicagoan.

There is, naturally, an inevitability to all this. We know, for example, that the conflict between these two women will eventually resolve into a genuine friendship; we know that there will be someone along eventually to explain the folksy relevance of the passion fish itself. But all the time we, the audience, can be confident that Sayles knows as well, here, with typical alacrity, writing and editing as well as directing in his usual calm, unfussy manner.

What marks this out then from what would otherwise be a 'crip-of-the-week' movie for the TV problem slot is the way in which Sayles orchestrates the whole with his unfailing eye. His (Oscar nominated) dialogue is, as ever, sharp and funny, allowing his characters to be self-pitying and harsh, but never at the expense of their essential humanity. Similarly, the performances could hardly be bettered - Woodard never once strays towards the kind of cliché that could so easily entrap her, remaining a suitably spiky foil for May-Alice's spite, but at the same time is allowed to develop her own character away from McDonnell, much to the film's credit. And McDonnell (who debuted in Matewan) found herself in the exalted company of the other Best Actress nominees at the 1993 Oscars, a prize which in all honesty she should have carried away for a performance that never once falls into the 'look at me' theatrics someone like Dustin Hoffman would bring to a similar male role. Sayles' regular David Strathairn - one of the most undervalued talents around - is a joy as Cajun odd-job man, Rennie.

There are problems, however. The essential predictability of the piece and its 135 minute running-time do tend to lead to an episodic nature that it never quite overcomes, and there is a slight feeling that Sayles is tipping his hat to box-office success a little too much here and there at the expense of the film. But such flaws are easily overlooked given the wonderful use of indigenous Cajun soundtrack, Roger Deakins' defiantly non-chocolate box photography, and the constant undercutting of easy sentimentality through the film's own built-in soap-opera metaphor. Scenes like visits to the house by May-Alice's old school friends and work colleagues ("I never asked for the anal probe!") are delicious in the extreme. This may not be the crusading John Sayles we've come to know (his next is a children's film), but it proves that even when he goes mainstream few, if any, can touch him.