In December 1995, Chuck Noland is a time-obsessed systems engineer who travels worldwide resolving productivity problems at FedEx depots. He is in a long-term relationship with Kelly Frears, with whom he lives in Memphis, Tennessee. Although the couple wants to get married, Chuck's busy schedule interferes with their relationship. A Christmas gathering with relatives is interrupted when Chuck is summoned to resolve a problem in Malaysia. While flying through a violent storm, his aircraft crashes into the Pacific Ocean. Chuck escapes from the sinking plane and is saved by an inflatable life raft, but loses the emergency locator transmitter. He clings to the life raft, loses consciousness, and floats all night before washing up on an island. After he awakens, he explores the island and soon discovers that it is uninhabited.
Several FedEx packages from the crashed plane also wash up on the shore, as well as the corpse of one of the pilots, Albert Miller, whom he previously befriended on the flight; Chuck buries the body with a makeshift tombstone. He initially attempts to signal for rescue and makes an escape attempt with the remnants of his life raft, but cannot pass the powerful surf and the coral reefs surrounding the island. He searches for food, water, and shelter, and opens the packages, making use of a number of items. He leaves one package, which has a pair of angel wings printed on it, unopened. During a first attempt to make fire, Chuck receives a deep wound to his hand. In anger and pain, he throws several objects, including a Wilson volleyball from one of the packages. Later, he draws a face in the bloody hand print on the ball, names it Wilson, and begins talking to it. One night, Chuck calculates that in order for the rescue workers to find the site of the plane crash, they will have to search an area twice the size of Texas, making his rescue unlikely.
Four years later (in early 2000), Chuck has adapted to the island's meager living conditions, having become adept at spearing fish and making fires. He also has regular conversations and arguments with Wilson, his only means of socialization. A large section of a portable toilet washes up on the island; Chuck uses it as a sail in the construction of a raft. After spending some time building and stocking the raft and waiting for optimal weather conditions (using an analemma he has created in his cave to monitor the time of year), he launches, using the sail to overcome the powerful surf. After some time on the ocean, a storm nearly tears his raft apart. The following day, as Chuck sleeps, Wilson becomes un-tethered and floats away from the raft. Chuck is awakened by the spray of a sounding whale, sees Wilson, and swims after him, but Wilson has gone too far to be safely retrieved and is lost at sea. Chuck returns to the raft and collapses in tears, overwhelmed by loneliness again. Later, a passing cargo ship finds him drifting and rescues him.
Upon returning to civilization, Chuck learns that he has long been given up for dead. His family and acquaintances have held a funeral, Kelly has moved on and has since married Jerry Lovett (a dentist who did a root canal on Chuck five years earlier) and has a daughter Katie. After reuniting, the pair profess their love for each other but, realizing they cannot be together because of her commitment to her new family, they sadly part. Kelly gives Chuck the Jeep Cherokee they once shared.
Some time later, Chuck travels to Canadian, Texas, to return the unopened FedEx package with the angel wings to its sender, a woman named Bettina Peterson. No one is home, so he leaves the package at the door with a note saying that the package saved his life. He departs and stops at a deserted crossroads a few miles away. A friendly woman passing by in a pickup truck stops to offer assistance, and explains where each road leads. As she drives away, Chuck notices angel wings on the back of her truck which match those on the parcel. As Chuck is left standing at the crossroads, he looks down each road, then smiles faintly as he looks in the direction the woman drove.
