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 re...

Having retrieved the plane tranceiver, a group of survivors try to transmit a signal, only to receive a strange transmission from another inhabitant.

Jack and Hurley discover an alarming secret about Kate, while the marshal's life hangs in the balance.

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 father. Things go wrong when he runs into the jungle after him. Claire has difficulties with her pregnancy.

Jin attacks Michael for seemingly no reason; Jack wants to move the survivors over to the caves, although some people disagree.

Charlie begins a journey of withdrawal from drugs aided by Locke, whose true motive is a mystery. Jack is buried alive in a cave collapse.

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.

Sayid's life is in danger after finding the source of the French transmission, while Hurley hatches a ridiculous plan to make life more civilized.

Claire has a horribly realistic nightmare about her baby being harmed, while flashbacks reveal her troubled past.

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.

Kate and Sawyer discover a briefcase and the race begins to win ownership of it. Charlie is still depressed over Claire, and is given a sharp talking to by Rose.

Locke plans to teach Boone a lesson, when he learns that Boone wants to share their secret with Shannon.

A mysterious island beast reappears when Michael and Locke clash. Sayid enlists Shannon to help decipher the French woman's map.

After Claire returns with no memory since the flight, Jack and Locke form a plan against her kidnapper, who threatens to kill the other survivors.

Sawyer believes that a boar is harassing him. So he and Kate go to find it. They bond on the journey. They run into Locke, who tells them a story that seems to mean something to Sawyer.

When the raft the survivors have been building burns down, Michael accuses Jin of sabotage. Sun makes a surprising revelation.

When Hurley becomes obsessed with the French woman and heads into the jungle to find her, Jack, Sayid and Charlie have no choice but to follow. Meanwhile, Locke asks Claire to help build a mysterious item.

Locke thinks he knows how to get the hatch open, and he and Boone venture inland. Jack is reluctant to help Sawyer get glasses.

Claire goes into labor while a helpless Charlie goes into panic mode. Meanwhile Locke is missing, Jack tends to a wounded Boone and Sayid presents Shannon with a romantic surprise.

After burying one of their own, tempers flare as the castaways' suspicions of each other grow -- and an unlikely survivor vows revenge. Meanwhile, Claire and Charlie struggle to calm her newborn.

Jack suspects foul play when Michael becomes violently ill while building the raft. Meanwhile a secret from Kate's past is revealed, the mysterious hatch is shown to a few of the survivors, and Walt gives Locke a warning.

The French woman arrives at the camp with a dire warning about a group of survivors known as the Others.

The castaways on the raft are surprised at sea by something unexpected. Meanwhile, remaining islanders attempt to blow open the hatch, and a visitor to the encampment might be a threat to Claire's infant son.

A visitor to the encampment could be a threat to Claire's son.