Eric Stoltz, who had a small but memorable role in Kicking and Screaming, plays Lester, an aspiring New York writer with a record of destroying relationships with worries about his partners' exes. When his current girlfriend Ramona (Annabella Sciorra) mentions that she used to date a now famous writer named Dashiell (Chris Eigeman), Lester feels so threatened that he joins Dashiell's therapy group, assuming the identity of his friend Vince (Carlos Jacott). While Vince hopes to get some vicarious help by having Lester talk over his problems in group, Lester unexpectedly becomes Dashiell's trusted confidant, and his crisis grows with his deception.

Mr. Jealousy takes place at some intersection where Whit Stillman's New York meets Woody Allen's. Baumbach's thirtysomething characters speak in complex literary sentences gleaned from their extensive education, but endearingly, they sometimes lose their way in a subclause before the thought is complete. Lester and Vince are entertainingly self-deluded, in a way that's particular to comedies about therapy groups: They make lots of ironic speeches about making progress and getting healthier. But Baumbach structures his farce so that, as a result of these sessions, the two men actually face the enemies they've constructed for themselves. If Lester sees his life as a New Yorker short story, complete with telling gestures and omniscient narrators, Baumbach shows us exactly how that perception makes him intellectualize his emotions. At the same time, though, the director uses that familiar narrative structure to bring Lester safely home.

Baumbach has assembled, in his two films, the core of a great ensemble. Stoltz adds subtle shadings to a role for which he's well-suited; Eigeman manages to be the slimy voice-of-his-generation at one moment and a sincere regular guy the next; and Carlos Jacott comes up with at least two extended comic scenes that snowball hilariously. The extra touches, though, make all the difference in expanding the insulated world of the writer-director and his characters. Bridget Fonda, in a brief cameo as a shy beauty with none of the pretensions or social skills of Lester and his group, elicits such emotion in a few sentences that the audience realizes just how much is at stake in these characters' search for happiness. Seeing themselves as the heroes of their private, tragic novels, they almost fail to discover the joy of being in a romantic comedy.