On a trip through Chile a boorish American expat named Jamie (Michael Cera) and three Chilean brothers plan to set off in search of the prized San Pedro cactus and its promise of beachy hallucinations. But in the previous night's drunken stupor Jamie invites a free-spirited fellow American (Gaby Hoffmann), whose devil-may-care worldview gives them more of an adventure than any of them had bargained for.