Howard Spence (Sam Shepard) has seen better days. When he was younger he was a movie star, mostly in Westerns. At the age of sixty, Howard uses drugs, alcohol and young girls to avoid the painful truth that there are only supporting roles left for him to play. After yet another night of debauchery in his trailer, Howard awakens in disgust to find that he is still alive, but that nobody in the world would have missed him if he had died.

Howard gallops away on his movie horse in full cowboy regalia; fleeing from the film and his life.

At an old train station, Howard trades in his costume for the shabby clothes of an old ranch hand (James Gammon) and travels to Elko, Nevada, the place that he ran away from years before and where his 80 year-old mother (Eva Marie Saint) still lives.

Mom takes him in and treats him as if he were still a boy. Perhaps Mom realizes that Howard is on the verge of a nervous breakdown. Meanwhile, the film shoot that Howard has abandoned is in chaos over his absence. The insurance company hires a private detective, Sutter (Tim Roth), to find Howard.

Mom tells Howard that more than twenty years ago a young woman called her up trying to locate Howard. Mom figured that the girl was pregnant. Howard is shocked at the thought that he has a grown child somewhere. This child could be a ray of hope, a possible salvation from his narcissistic and meaningless life. When Sutter appears in Elko, reminding Howard of the reality he has escaped from, he flees again, this time to find his child.

His destination is Butte, Montana, the location twenty five years earlier where Howard shot the movie that made him a star. It was also where he had an affair with Doreen (Jessica Lange) who then, and now, is the waitress at the local coffee shop. She has a son, Earl (Gabriel Mann), a rock musician and singer living in Butte with his girlfriend Amber (Fairuza Balk). Howard's meeting with Earl is violent and unsettling.

Earl completely rejects this unknown father who appears too late in his life. Saddened by this encounter, Howard is ready to give up and leave Butte again, when out of nowhere a young woman named Sky (Sarah Polley) appears. She is exactly the same age as Earl. She is, in fact, Howard's child, the product of another short fling that happened during the filming of the same movie. She is Earl's half-sister. These siblings do not know about each other. That's when the real complications of this American family reunion begin...