Kat Ellis (Debra Messing) is a single New Yorker who returns to her parents' house in London to be the maid of honor at her younger half sister Amy's (Amy Adams) wedding. The best man is none other than her former fiancé, who unexpectedly dumped her two years ago. Anxious about confronting him and eager to impress him, she hires suave escort Nick Mercer (Dermot Mulroney) to pose as her boyfriend.