Where Do They Start? On Fat Tuesday, during the New Orleans Mardi Gras, where Special Agent Doug Carlin (Denzel Washington) is investigating a terrorist attack.Where Do They End Up? Via the revolutionary Snow White program, Doug can see and eventually visit the past up to four days previously.Biggest Culture Clash. Doug gets romantically attached to Clare (Paula Patton), one of the victims of the bomb blast.Unresolved Paradox. Doug saves Clare at the expense of his own life and then the next person Clare meets is Dougs past self.