For Tammy, a burger-joint employee, a bad day keeps getting worse. She wrecks her car, loses her job and finds that her husband has been unfaithful. It's time for Tammy to hit the road, but without money or transportation, her options are limited. Her only choice is a road trip with her hard-drinking grandmother, Pearl, who has a car, cash and an itch to see Niagara Falls. It's not the escape Tammy had in mind, but it may be what she needs. After getting fired and finding out that her husband is cheating, Tammy hits the road with her profane, alcoholic grandmother.