Lost is an ABC sci-fi drama that follows the lives of plane crash survivors on a mysterious island. Each episode typically features a primary plot line with the characters on the island, as well as supplementary flashback sequences from another point in one of the characters' lives.
Despite a lackluster stretch in the third season, Lost remains one of TV's best dramas. Rent the DVDs and start watching it from the beginning if you haven't yet.
Just be prepared to wave goodbye to your social life.