Gwen Cummings (Sandra Bullock) is a sucessful NY author who's everyone's favourite party girl.
Life to Gwen and her boyfriend, Jasper (Dominic West), is just a fun-filled exercise in debauchery. The pair spend their social life stumbling from bar to night-club to hangover.
However when Gwen's alcohol-fuelled display at her sister Lily's (Elizabeth Perkins) wedding results in her stealing a limousine and crashes into a house. This leads to a drink-driving charge, a court orders her to spend 28 days in a rehabilitation centre.
Determined she does not belong, Gwen refuses point blank to conform to the clinic's unique set of rules and rituals she is faced with.
It's only through the relationships she forms with the other patients and her counsellor, Cornell (Steve Buscemi) that she begins to realise that there may be more to life than being the life and soul of the party.