Sometimes the right part comes along at the right time for the right actor, and the film that results from it forever changes his or her career. That’s exactly the case with Matthew McConaughey in Dallas Buyers Club as he takes on the role of AIDS activist Ron Woodroof, and in the process proves himself to be that rare combination of movie star and serious actor that he’s always threatened to become. Ron is a good-old-boy Texan who, in 1986, is diagnosed with AIDS. At that time, far less was known about how to treat patients; his doctors want him to take doses of AZT, which could help combat the disease, but might also make Woodroof -- who already suffers from an immune deficiency -- much more vulnerable to its side effects. He soon learns about Dr. Vass (Griffin Dunne), who has devised a cocktail of vitamins and other medications that have proven effective in treating AIDS patients. Complicating matters is the fact that Vass’ clinic is located in Mexico because he utilizes drugs that have not yet been approved by the FDA. Ron devises a scheme to bring these medications into the United States while avoiding prosecution for selling illegal drugs, and forms a “buyers club” whereby the membership fee grants the individual access to the life-saving materials. As the federal government, state health officials, and his own sympathetic but rules-oriented doctor (Jennifer Garner) try to stop him, Ron battles the disease by himself and tries to help out his fellow patients, including his second-in-command Rayon (Jared Leto). Dallas Buyers Club wants to tackle a very serious issue in a very serious manner. In lesser hands, it would be the kind of movie that demands you forgive any of its faults because of its importance. Thankfully, McConaughey keeps the whole project from being just a do-gooder chore. He grabs the viewer from the first scene, in which Ron gets ready to compete in a rodeo, and never lets go. He uses his commanding physicality differently here than he has in the past, dropping a bunch of weight so we see how the disease has ravaged his character’s body. However, even at Ron’s weakest, McConaughey makes sure that we can always see his fierce will to live -- and to live on his own terms -- in his eyes. As an actor, McConaughey can mix that life spirit with anger, caustic wit, or steely resolve whenever necessary. He demands your attention because his character is so focused: He wants nothing more than to live and to help others do the same. The only time we aren’t riveted by his every word and gesture is when he shares the screen with Leto, who turns what could have been a stereotypical role -- the flamboyantly effeminate and often claws-out bitchy Rayon -- into a harrowing portrait of a life robbed of the chance to flourish. He’s nearly unrecognizable, and together he and McConaughey bring complicated and messy human emotions to a movie that could have easily turned into an earnest bore. Screenwriters Craig Borten and Melissa Wallack find moments of humor throughout, especially in the many ways Ron outwits the tenacious federal agents assigned to stop him. They also give the film a sense of momentum that’s driven by Ron’s efforts to create and build the buyers club, preventing the movie from becoming the story of watching Ron get sicker and sicker. That aspect of the script dovetails with director Jean-Marc Vallee’s approach, which neither flinches from nor wallows in the effects of AIDS on the characters; his innate humanity shines through in every scene. As good as everybody who worked to make Dallas Buyers Club is, this is McConaughey’s movie through and through. Since 2011, no actor has had a more career-changing run of films than he has. He’s shed the baggage of too many pedestrian romantic comedies with meaty roles in challenging and interesting pictures like Bernie, Killer Joe, Mud, and Magic Mike -- the last one earning him a well-deserved Best Supporting Actor trophy at the Independent Spirit Awards. His performance in Dallas Buyers Club not only feels like the apex of this period of his career, but the moment when all of those old comparisons to Paul Newman start looking more and more accurate.