American pharmacologist Elmo McElroy (Samuel L. Jackson) has created a powerful new party drug called POS-51 and is now on his way to Liverpool, England, where he hopes to sell the formula to crimelord Leopold Durant (Ricky Tomlinson). When he arrives, Durant's henchman Felix DeSouza (Robert Carlyle) escorts him to the meeting, which quickly disperses when assassin Dakota (Emily Mortimer) makes an attempt on the American's life. In the midst of the ensuing chaos, McElroy and DeSouza team up and begin looking for a fresh buyer for POS-51.