Chuck Noland (Tom Hanks) is a time-obsessed FedEx systems analyst, who travels worldwide resolving productivity problems at FedEx depots. He is in a long-term relationship with Kelly Frears (Helen Hunt), with whom he lives in Memphis. Although the couple want to get married, Chuck\'s busy schedule causes problems. A Christmas with relatives is interrupted by Chuck being summoned to resolve a problem overseas. At the airport, the couple exchange Christmas gifts. Kelly gives Chuck her grandfather\'s pocket watch with her picture in it, and Chuck gives her what appears to be a ring, which he tells her to open on New Years, after he returns.
While flying through a violent thunderstorm somewhere over the southern Pacific Ocean, apparently having flown off course, an incident occurs on Chuck\'s MD-11 which results in it crashing into the ocean. Chuck is able to escape the sinking plane and is saved by an inflatable life-raft, which floats for some time in the storm before being washed up on an island.
It soon becomes clear that the island is uninhabited, and Chuck\'s early attempts to make visual signals for any searching aircraft, and to escape the island in the remnants of his life raft are fruitless.
After several FedEx packages from the crashed plane wash up on the island, Chuck begins to open them, looking for items to use for his survival. He finds a number of potentially useful items but leaves one package, painted with a pair of wings, unopened.
During a failed attempt to make fire, Chuck receives a deep wound to his hand. In anger he throws several objects, including a Wilson volleyball from one of the FedEx packages. A short time later he draws a face in the bloody hand print on the ball, naming it \"Wilson\" and talking to it as if it were a person.
The film shifts forward by four years to show Chuck now dramatically thinner and bearded with longer hair and wearing a loincloth. He has become an expert at spearing a fish and eating it raw. It becomes clear that in the intervening time Chuck has not only become proficient at surviving in the island environment, but has also developed a deep attachment to Wilson, regularly having \"conversations\" with him and becoming distressed when he is seemingly lost.
After a large sheet of plastic from a portable toilet washes up on the island, Chuck decides to use it as a sail in the construction of a raft. After spending some time building and stocking the raft (including food, fishing equipment, oars and the unopened package) and deciding when the weather conditions will be optimal, Chuck launches the raft and finally escapes the island. During the escape, he encounters a passing whale. After some time on the ocean, the raft is virtually destroyed by a storm which ultimately results in Wilson being lost.
Distraught, Chuck resigns himself to his fate and abandons his attempt to find rescue. Half-dead and sunburned, he is found drifting a short time later by a passing cargo ship with the whale waking him up. Upon returning home Chuck discovers that he has long been given up for dead by everyone he knows; his family and friends held a funeral, and Kelly has since married and had a daughter. After meeting Kelly the pair profess their love for each other but realize a future together would be impossible; they part, Kelly giving Chuck their Jeep Cherokee which she had kept. Chuck remarks to a friend that he has now \"lost her all over again,\" having previously resigned himself to being stranded on the island for the rest of his life.
Chuck then travels to the address on his unopened package to return it. The house is empty so he leaves the package at the door, with a note telling the occupant that the package saved his life. He then departs, stopping at a remote crossroads. A woman passing by in a truck stops to explain where each road leads. As she drives away Chuck, standing at the crossroads, notices an illustration on the back of the womans departing truck that is similar to one seen at the house and on the parcel. The film ends with Chuck looking down each road, trying to decide which direction to go. Then the camera comes to his face as he looks up the road of the departing truck, with a faint smile.