In 1977, 18-year-old Scott Thorson (Matt Damon), who works as an animal trainer for films, meets Bob Black (Scott Bakula), a Hollywood producer, in a gay bar in Los Angeles. At Black’s urging, he leaves his adopted home in search of better-paying work. Black introduces Thorson to Liberace (Michael Douglas), who takes an immediate liking to the handsome younger man. Liberace invites the two backstage and then to his luxurious home in Las Vegas.
Thorson observes that one of Liberace’s beloved dogs is suffering from a temporary form of blindness, and with his veterinary assistant background, informs the famous pianist that he knows how to cure the condition. After treating the dog, Thorson becomes Liberace’s “assistant” at the performer’s request. Thorson also becomes employed as Liberace’s stage chauffeur, driving a Rolls-Royce limousine onto the stage for Liberace’s grand entrances.
Thorson moves in with Liberace and becomes his lover. At this point, Thorson says that he is bisexual because he is also attracted to women. Liberace is sympathetic, informing him that he wanted and tried to love women, but was exclusively attracted to men. He relates a story of a “divine healing” in which a “messenger” informed him that God still loved him.
It gradually becomes clear that Liberace is trying to mold Thorson into a younger version of himself. He asks his plastic surgeon, Dr. Jack Startz (Rob Lowe), to transform Scott’s face to more closely resemble his own and makes an unsuccessful attempt to formally adopt him. Thorson soon turns to drugs (begun by his usage to recover from his surgery) as he becomes more angry and frustrated with Liberace trying to control him as well as Liberace’s obsession to publicly hide their romance at any cost.
By 1982, Thorson’s increasing drug abuse and Liberace’s interest in younger men, including dancer Cary James (Boyd Holbrook), creates a rift that ultimately destroys their relationship. When Liberace begins visiting pornographic peep shows and suggests that they each see other people, Thorson becomes upset.
Scott Thorson retains an attorney to seek his financial share of the property by suing Liberace for over $100,000,000 in palimony. As a result, Liberace ends their formal partnership and involves himself with his most recent, and much younger, “assistant”. In 1984, Thorson’s palimony lawsuit starts where he gives details about his romance for five years with the entertainer, while Liberace flatly denies any sexual relationship.
Not long thereafter, in December 1986, Thorson receives a telephone call from Liberace telling him that he is very sick with what is later revealed to be AIDS and that he would like Thorson to visit him again. Thorson agrees and drives to Liberace’s retreat house in Palm Springs, where he and Liberace have one last, emotional conversation. Liberace dies a few months later in February 1987. Thorson attends Liberace’s funeral, in which he imagines seeing Liberace performing one last time with his traditional flamboyance, before being lifted to Heaven with a stage harness.