
Survivors of a plane crash find themselves on a mysterious tropical island.

The survivors organize and make a shocking discovery via a radio transmission.

Jack discovers Kate's secret past. The marshal struggles to survive.

Locke goes on a boar hunt. His backstory reveals a life-changing secret.

Jack chases a vision into the jungle while the survivors face a water crisis.

Sun's hidden talent is revealed. The survivors debate moving to the caves.

Charlie struggles with his addiction. Jack is trapped in a cave collapse.

Sawyer is suspected of hoarding medicine. His backstory reveals a troubled origin.

Sayid encounters the woman behind the distress signal.

Claire has disturbing dreams. A stranger among the survivors is discovered.

Jack and Kate search for kidnapped survivors. A major discovery is made underground.

Kate and Sawyer fight over a mysterious briefcase. Shannon helps translate maps.

Boone and Shannon's complicated relationship is explored.

Michael and Walt's strained relationship is tested. Walt may have unusual abilities.

Claire returns with no memory. The survivors prepare for Ethan's return.

Sawyer hunts a boar that seems to be targeting him. A drinking game reveals secrets.

Jin's perspective on his marriage to Sun is revealed. The raft is sabotaged.

Hurley recognizes a sequence of numbers on Rousseau's maps and becomes obsessed.

Locke and Boone work to open the Hatch. Locke's tragic family history is revealed.

Jack fights to save a life while a new life arrives on the Island.

Sayid investigates Locke's role in Boone's death. Tensions rise.

Kate tries to secure a spot on the raft. Someone poisons Michael.

Rousseau arrives with a warning. The raft launches. The expedition to the Black Rock begins.

The first season reaches its climax. The raft encounters danger. The Hatch is opened.

The aftermath of the season's climactic events.