A London nurse (Minnie Driver) and her best friend, an American actress (Mary McCormack), overhear a bank heist in progress on a cell phone; when their efforts to alert the police are rebuffed, they decide to blackmail the thieves by making anonymous threatening calls to the same phone number. Kim Fuller’s script is hectic and inventive, although Fuller’s constantly switching from high farce to sinister melodrama and back again is a bit more than director Mel Smith can handle. As a result, the film suffers from drunken pacing and baffling changes in tone. Still, it gets by on star power: Driver and McCormack make appealing heroines, and Kevin McNally and Michael Gambon are gratifyingly menacing villains. Kevin Eldon and Mark Williams wander in and out of the action as two clueless cops.