Matthew McConaughey stars in “Dallas Buyers Club” as real-life Texas cowboy Ron Woodroof, whose free-wheeling life was overturned in 1985 when he was diagnosed as HIV-positive and given 30 days to live.

LOS ANGELES — Few actors can play a grifter and a good ol' boy with the laid-back precision of Matthew McConaughey. Between the sidewinder glances, the sardonic grin and that slippery Texas drawl, he uses irony, edge and considerable charm to move us into taking his most questionable characters seriously, while we forgive their indiscretions.

McConaughey needs all of those substantial powers of persuasion for the gutsy, gritty “Dallas Buyers Club.” He portrays a hard-bitten, hard-drinking, homophobic Texas redneck named Ron Woodroof, who becomes an unlikely warrior on the front lines of AIDS. Jared Leto as Rayon, a willowy transsexual who favors hot-pink lipstick, plunging necklines and heels, matches him biting aside for aside. Together they elevate the movie beyond ordinary biography, and give Oscar-worthy performances in the process.

Directed with an unsentimental hand by Jean-Marc Vallee, from Craig Borten and Melisa Wallack's smart screenplay, this cut at the AIDS crisis is marked by unexpected humor and roughneck rebellion as well as heart-wrenching humanity.

The movie follows Woodroof from his HIV diagnosis in 1985 to his death seven years later — long past the 30 days the doctors first gave him. In Ron, the filmmakers have the ideal embodiment of macho outrage. In real life, Woodroof used it to fuel his fight against disease and the Food and Drug Administration, which expended a great deal of energy to slow approval and shut down access to experimental drugs, even as the death toll mounted. Besides AIDS, the agency is the film's primary enemy. Much of the movie's conflict is linked to Woodroof's confrontations with FDA official Richard Barkley (Michael O'Neill), both trying to outmaneuver the other.

But Ron's anti-gay bias serves another purpose. The film uses his paranoia to expose the raw nerves of the country circa 1985, when fear of accidentally contracting HIV ran high and misconceptions about homosexuality were rampant. It is telling that when his doctors — Dr. Sevard (Denis O'Hare) and key researcher Eve (Jennifer Garner) — diagnose HIV, the panic and anger that follow are bound up in Woodroof's fear that someone might think he is gay.

Though the films opens with a death sentence, “Dallas Buyers Club” is really about beating the odds. Woodroof is determined to find, use and also sell the most promising AIDS cocktails. The search for the latest meds takes him from Mexico to Japan to Germany, with the authorities nipping at his heels. Their skirmishes put on trial Big Pharma's role in the development and distribution of AIDS drugs, and the FDA's red tape.

The human story is the more interesting one.

HIV does not turn Woodroof into the understanding type, not even when lifelong friends desert and ridicule him. What ultimately softens Woodroof is Rayon. They meet in the hospital's AIDS ward. Their relationship begins as a testy business arrangement, a way for Woodroof to sell bootlegged AZT to the gay community. That leads to the creation of the Dallas Buyers Club, where a $400 membership comes with a month's supply of medication.

Over time, their bond evolves into a real friendship that somehow exists alongside the biases Woodroof can't quite let go. It's a credit to both actors how well they walk the love-hate line.

To play a dying man, McConaughey dropped enough weight to look as if he is at death's door, as did Leto. Both are gaunt, with McConaughey's weight loss so extreme as to border on distraction.

Leto's performance, though, is the revelation. He's tended to be more of an ensemble player in films such as 1998's “The Thin Red Line” or 2000's “Requiem for a Dream.” Rayon should change all that. It's a hauntingly authentic performance; the tailored suit he puts on to meet with his disapproving father is one of the film's most moving scenes.

Meanwhile, Vallee lets the bureaucratic bad guys played by O'Neill and O'Hare, whose doc is desperate to keep his clinical trials going, get far too close to parody. Compared to the French Canadian director's earlier work “Dallas Buyers Club” is by far his most challenging film. And though it represents a career high, at times it gets the best of him.

Ultimately, the movie's strength lies in the performances of McConaughey and Leto. The actors bring a kind of flinty resilience to their characters despite a relentless disease and an irreversible fate. Not always easy to witness.

<B>TITLE:</B> “Dallas Buyers Club”<B>CAST: </B>Matthew McConaughey, Jared Leto, Jennifer Garner and Steve Zahn<B>DIRECTOR: </B>Jean-Marc Vallee<B>RATED: </B>R for “pervasive language, some strong sexual content, nudity and drug use.”<B>GRADE: </B>★★★★ (out of 5)