Ad executive Charles (Clive Owen) and business woman Lucinda (Jennifer Aniston) meet on a commuter train in Chicago. Despite both being happily married, their flirtation escalates into something more. Unfortunately for the new couple, a ruthless criminal is aware of their relationship, and he threatens to expose the pair if he is not paid. With their families at risk, Charles and Lucinda must try and find a way to turn the tables on their blackmailer.