In 1997, Greg Sestero, an aspiring actor struggling with confidence, first encounters Tommy Wiseau in an acting class held by Jean Shelton in San Francisco.

Sestero is initially perplexed by Wiseau's over-the-top acting technique, unusual physical appearance, untraceable accent, and eccentric behavior, which includes a fascination bordering on obsession with American culture and a refusal to discuss his past.

Backed by a mysterious, seemingly endless supply of money, Wiseau develops, produces, directs, and stars as the lead role in The Room, despite having no knowledge of filmmaking whatsoever.

By the end of the shooting, Sestero, along with the rest of the cast and crew, become convinced that the film is merely a vanity project for Wiseau that will never actually be seen by anyone and lose their enthusiasm, resulting in lackluster performances and technical and storytelling blunders that prove impossible to correct in post-production.

To lift Sestero's morale, Wiseau writes additional scenes for them to perform during second unit filming in San Francisco, which runs considerably smoother, to everyone's surprise.

These recollections are occasionally interspersed with "fantastical, sad, self-contradictory stories" about Wiseau's conflicted past, which apparently includes such experiences as being ridiculed for his interest in America while growing up in an unidentified Eastern Bloc country, being threatened with death by sadistic French policemen, and quietly progressing from a yo-yo and toy bird salesman to a retail and real estate tycoon, which serve to highlight his motivations for attempting to enter the film industry.