Sam (Christian Bale) and Alex (Kate Beckinsale) are a newly engaged couple who move to Los Angeles to further their careers. Sam is a recently graduated psychiatrist, starting his residency, while Alex, who comes from a very wealthy background, is finishing her M.D.-Ph.D. dissertation on genomics. The relatively strait-laced, upwardly mobile couple plan to stay at the vacant home of Sam's mother, Jane (Frances McDormand), a free-spirited record producer in the Laurel Canyon section of the City of Los Angeles.
In a change of plans, however, Jane is still around, recording an album with her boyfriend, Ian McKnight (Alessandro Nivola), and his band. The film focuses in some depth on the challenge of trying to create successful pop music, showing work on two tracks (both actually written, and previously released, by the band Sparklehorse). Ian's bandmates are played by noted indie rockers, bassist Lou Barlow and guitarist Imaad Wasif.
Jane and Ian are in the midst of a fiery romance, and both the producer and the band seem more interested in partying than finishing the record. Jane's presence is a source of consternation for Sam, as he and his mother have a somewhat strained relationship, due to their very different mindsets.
Alex, however, is intrigued by the new lifestyle options presented by her soon-to-be mother-in-law. Normally hardworking, Alex begins spending more time with the band and less time working on her dissertation. Her growing fascination with Jane and Ian leads to a scene where the three of them kiss one another while naked in the swimming pool.
Meanwhile, Sam finds himself attracted to fellow resident Sara (Natascha McElhone), who is unapologetically interested in him as well. They share one first kiss while returning from an informal interns' meeting, around the same time Alex has her first tryst with Jane and Ian in the pool. Some time later, while Alex attends Jane and Ian's party held in a crowded hotel suite to celebrate the band's new album release, Sam and Sara meet in a parking lot and, in a conversation filled with sexual tension, they declare their attraction for one another.
The situation strains Sam and Alex's relationship almost to the point of breaking by the end of the film. After the party has finished and the three of them are left alone in the suite, Ian tries to "finish" (in his words) his encounter with Alex and Jane, but the latter decides against it and the threesome does not take place. Upon returning home after his conversation with Sara, Sam decides to go to the hotel and discovers Jane, Ian, and Alex scantily-clad in the bedroom. In a fit of rage he repeatedly punches Ian, hits his mother with the elbow as she tries to split the fight, and leaves the hotel, but Alex chases him down the street and professes her love for him.
The next morning, the situation seems back to normal again. But Sara phones Sam and tells him she can't control her heart, as opposed to what he told her the day before. Sam watches his surroundings, postpones any further conversation, and takes a moment of reflection. Credits run.Frances McDormand as Jane
Christian Bale as Sam
Kate Beckinsale as Alex
Natascha McElhone as Sara
Alessandro Nivola as Ian McKnight
Lou Barlow as Frip
Imaad Wasif as Dean
Russell Pollard as Rowan
Mickey Petralia as Mickey
Melissa De Sousa as Claudia
Lisa Cholodenko stated that the film was inspired by the Joni Mitchell album Ladies of the Canyon. The script was workshopped at Sundance Institute's lab.