Forty-eight survivors of an airline flight originating from Australia, bound for the U.S., which crash-lands onto an unknown island 1000 miles off course, struggle to figure out a way to survive while trying to find a way to be rescued.
When the survivors run out of food, Locke, Kate, and Michael go out hunting for boar. Michael gets injured, so he and Kate go back. But Locke stays out hunting, and ends up running into the creature living in the jungle.
Jack begins to experience visions of his dead father Christian. He runs into the jungle trying to find him, but things go wrong when he falls down a hill and off a cliff.
Shannon is having an asthma attack and Boone is sure that Sawyer has her medication. As Kate's way of dealing with this situation doesn't work, Sayid takes things into his own hands.
Jack, Kate, Locke and Boone go after Ethan, Claire and Charlie. They separate, and while Jack and Kate confront Ethan, Locke and Boon find another mystery at the jungle. Flashbacks reveal more about Jack's past with his dad.