Everyone, at some point in his life, has known a Withnail -- or should have. The lead character in the Bruce Robinson film "Withnail and I," Withnail (Richard E. Grant), is one of those attractive, posturing, larger-than-life figures we sometimes run into in our youth, when everything lies ahead and little or nothing of substance has yet been accomplished. It's a time when attitude counts for everything -- and Withnail has a lot of attitude.

Withnail is so universal a type, and so engaging, that it's remarkable he's never been given his full due on screen. He has now, though, and Robinson, who wrote the script as well as directed it, has created him vividly, with all sides of him turned toward us at once.

The movie, which is Robinson's first, is a cuttingly smart comedy about a pair of youngish actors in London in 1969. Withnail, dressed in a long coat and flowing scarf, looks like some figure out of Dickens, a cross between the Artful Dodger and The Cat in the Hat. And he seems cloaked in tragic glamor, like a mod Byron. His dialogue has a theatrical cut and flair -- a sort of Oscar Wildeian bitchiness.

Withnail's Boswell, the film's "I," is an observant, pensive sort peering out from behind round-rimmed glasses. Though he's never identified in the movie, his name -- the production notes tell us -- is Marwood, and he gives the film its emotional center. Marwood observes the events of their miserable life together, laying them down in his journal and reporting to us, periodically, in voice-over.

Tall and sleekly built, with a matinee idol's striking profile, Withnail seems ideally suited for success -- a born star. Everything about him is exaggerated, overdramatized. "Look at my tongue," he says to Marwood. "It's wearing a yellow sock." Freezing and "sick as a pike," he screams for alcohol, and finding every bottle empty, he unscrews the cap on a tin of lighter fluid and downs it. Next, he lunges for the toolbox -- antifreeze! -- but Marwood stops him. "You bloody fool," he says, "You should never mix your drinks."

This self-dramatization -- which the film presents partly as an actor's way of keeping in shape, and partly as thespian histrionics -- is the source of the movie's comedy. Both Marwood and his friend specialize in acting-out, but Withnail is the past master. His every gesture is an act of self-styling, and watching him, you feel that it's not so much him you're seeing as his theatrical projection of himself, his performance of himself. And, indeed, it's a great performance -- mercurial, flamboyant, grand. But his tragedy comes in the awareness that it's the only role he'll ever play, that he's trapped in his own character.

The two are ideally suited for one another, for what Withnail needs most of all is an audience. He's an actor to his marrow, and, though he is without work -- and has been for some time -- is irrefutably, in his own mind, a great one. He's a bit of a poseur -- a sort of genius manque'.

What Marwood needs is a mentor -- someone to introduce him to the things that his own background has passed over. The relationship between the two is filled with unresolved tensions and jealousies. And Robinson, who was an actor before he turned to writing -- he's best known as Captain Pinson, Isabelle Adjani's love object in "The Story of Adele H" -- knows how to keep the subtext emotions bubbling.

This is a remarkably accomplished outing for a first-time director. (Robinson is known primarily as a screenwriter, and his script for "The Killing Fields" earned him an Academy Award nomination.) But though the film has a terrific look -- it captures perfectly that wet, bleu-cheesy look of English weather -- and a poised, smooth-flowing style, it's very much a writer's movie, made with a writer's eye for detail.

The film covers that invaluable down time in life after school is finished and life hasn't really started. The two men share an apartment that is essentially a cage, a squalid prison littered with empty wine bottles and brimming sinks and ashtrays. They're miserable, strung out on speed and unable to sleep, but their misery is dear to them; it gives them something to play off of. Yet, for Marwood, the charm has worn thin, and play misery has given way to real suffering; he's ready to move on, to do something with his life.

The bulk of the film takes place in the English countryside near Penwith in a cottage lent to them by Withnail's wealthy Uncle Monty (Richard Griffiths). The piggy Monty is a great cartoon of a character -- a raging, queeny, caricature of English upper-class pederasty. And Griffiths is terrific in the role -- truly revolting and truly touching.

The scenes in the cottage, especially the one in which the actors try to prepare a live chicken for dinner, have their own giddy, baroque sense of what's funny. The movie does drag some during this section, and some of the sequences don't come to much. And the scenes in which Monty, besotted with Marwood and wearing blue eye shadow, tries to corner him, are clumsy and a little vulgar.

When a director who was formerly an actor is able to get great performances out of his cast, it shouldn't be a revelation, but here it is. Both leads, Richard Grant and Paul McGann, are new to film, and because they give such confident, controlled comic performances, it seems near-impossible that they're not already established stars.

Grant, in particular, shows a real verve and command. His Withnail is all spleen and cowardice, and still retains his crumbling grandeur. And McGann, in the tougher, more recessive role, makes Marwood's sanity, his ability to see through Withnail and untangle himself from him, palpable from the start. Because of it, we see early on what will happen to the two friends -- that Marwood, though less obviously well-endowed, will prosper, and the gifted, screwed-up Withnail founder.

Robinson adds an additional layer of meaning by placing his story in 1969, only days before the end of what the film's visionary/doper character, Danny, (played in a kind of acid haze by Ralph Brown) calls, "the greatest decade in the history of mankind." His evocation of the period is glancing, subtle, unsentimental. But it's enough.

When Marwood breaks up the team, after getting his big break as the lead in a play in the provinces, he's moving beyond both Withnail and the '60s. And it's a kind of death. Afterward, Withnail is left alone in Regents Park, drunk, in the pouring rain, reciting the "What a piece of work is man" speech from "Hamlet," with only the wolves at the zoo to hear his howlings. "Man delights me not -- nor women neither," he laments. "Nor women neither." Wandering off, umbrella in hand, he's a figure of great poignancy, of wasted talent and lost youth; more dust than its quintessence -- a rogue and peasant slave, indeed.

Withnail and I, at the Key, is rated PG and contains some suggestive language and situations.