Margot (Nicole Kidman), a novelist with a disconcerting habit of sticking a verbal knife into people, shows up at the house of her unhappy sister, Pauline (Jennifer Jason Leigh), who is about to marry an out-of-work rocker (Jack Black).
The practice seemed to have been allowed before statehood, and had been used for soldiers during the Second World War, but no one knew exactly why it had arisen: possibly because it was difficult to travel long distances to a courthouse to marry an out-of-state sweetheart.