Rachel Buchman (Rosemarie DeWitt) has planned her wedding down to the last detail, she wants everything to be perfect. But when her sister Kym (Anne Hathaway) comes home for the big day, all sorts of problems come with her. Kym is always in the midst of a crisis. She has a rather bizarre sense of humor and as the family drama queen, she finds herself in the middle of every conflict. Rachel’s idea of a wonderful wedding with her friends and family just may not come off with a hitch if Kym can’t get herself and her issues under control.