Two twins lead separate lives since one of them blamed the other for the accidental death of his father. Years later, one carries a conventional family life while the other has a life of excess. When the first has an accident and is in a coma, the other does not scruple to take over her identity and steal her life.

Zack and Cody Martin are aboard the SS Tipton, a luxury passenger cruise liner owned by London's father. The ship cruises the world with tourists and students who attend classes at Seven Seas High, the one high school that London's dad thinks will make his daughter a better student. While out at sea, Zack and Cody still have their compass pointed towards mischief, and London learns to live a "fabu-less" lifestyle, including sharing a small room with Bailey, a country girl from Kansas.