Chuck Noland (TOM HANKS) is a systems engineer for Federal Express who works and lives by the clock. Jaunting around the world with fellow employee Stan (NICK SEARCY) and instructing international centers how their package delivery system works, that one lives or dies by the clock, and that it's a sin to loose track of time, Chuck barely has time for his girlfriend back in Memphis, Kelly Frears (HELEN HUNT).
Although he gets back in time to be with her on Christmas Eve, Chuck gets a page that he must leave for yet another job. Telling her he'll be right back after giving her what she assumes to be an engagement ring but is afraid to open, Chuck heads off on his flight over the South Pacific.
Encountering a bad storm, the small crew of the FedEx plane diverts off their course to get around it, but ends up crashing, with Chuck being the sole survivor. Washing up onto the shores of a tropical island, Chuck is happy to be alive, but soon finds that he's all alone on an uninhabited isle, with nothing but water surrounding him and only a few remnants of civilization to help him survive.
Nevertheless, he does just that, learning how to build shelter, hunt for food, start a fire and overcome the rampant loneliness that descends over him day after day, month after month, and year after year. As he does so, he hopes that at some point he might be rescued, not realizing what might then lie in wait for him after being gone for so long.