Dallas, 1985: Cowboy Ron Woodroof (Matthew McConaughey) leads an excessive life in the fast lane. Rodeos, alcohol, coke and women determine his everyday life. When Woodroof ends up in the hospital because of a fight, the doctor tells him after a routine examination that he is HIV-positive and has only 30 days to live. The world of the homophobic Texan collapses - for him it is inconceivable that he should have been infected with this "gay disease". After the only legal drug AZT prescribed by his doctor Dr. Eve Saks (Jennifer Garner) does him more harm than good, he looks for alternatives. Ron finds what he is looking for in Mexico and begins smuggling the drugs, which are illegal in the U.S., into the country on a large scale. To make his business even more lucrative, he gets involved in a deal with transgender Rayon (Jared Leto): Together they found the "Dallas Buyers Club", whose paid membership gives unlimited access to the preparations. With the business of their lives, a special relationship gradually develops between the formerly reckless hedonist and the sensitive transsexual. The club becomes nationally known in no time at all, and the flat-rate medications sell like hot cakes among Ron and Rayon's fellow sufferers. With its success, however, the organization quickly finds itself in the sights of the FDA (Food and Drug Administration). The health authorities are not willing to give up the profitable business with the sick, just as the pharmaceutical industry is. Ron decides to go against the system and fight not only for the right of the sick, but for life.