Locke persists in his obsession with exploring the cavern below the hatch, despite the fact that it cannot provide everyone with shelter for the night -- and Kate agrees to descend into the hole.
Michael and Sawyer brave the open water after the raft is destroyed, with no sign of Jin. Locke follows Kate into the hatch, only to find himself a prisoner of its enigmatic resident.
Locke and Kate must find a way to repair the computer inside the hatch, though Jack believes that nothing will happen when the timer reaches zero. Sawyer, Michael, and Jin are captured and held by people they believe to be the mysterious "Others."
Hurley is assigned to inventory the food stockpile inside the hatch, bringing up memories about the day after his big lottery win. Michael, Jin, and Sawyer learn more about their captors.
Jin follows Michael into the jungle when he escapes their captors and goes looking for his son. Sun panics when she discovers her wedding ring is missing.
Shannon continues to see visions of Walt and strikes out on her own to find him. Charlie grows jealous of Locke's interest in Claire, while the tail section survivors continue their dangerous march through the jungle.
When Oceanic Flight 815 crashes on the island, Ana Lucia and the other survivors of the tail section fight to survive when the mysterious Others begin abducting them -- and infiltrating their ranks.
Ana Lucia holds Sayid at gunpoint after killing someone close to him, forcing her to relive her troubled past as a police officer. The tail section survivors are reunited with the rest of the castaways.
When Mr. Eko discovers that Charlie is in possession of the Virgin Mary statue, he forces him to lead him to the site of the plane crash -- with which Eko himself has a past connection.
Jack, Locke, and Sawyer go after Michael when he takes a gun and disappears into the jungle to try and find Walt, and find themselves in a confrontation with the Others. Jack recalls the fate of his marriage.
Sun is injured in a failed abduction, leading the castaways to fear that the Others may have returned. Jack and Ana Lucia have trouble finding volunteers for their army, and Sawyer recalls a past con.
Rousseau leads Sayid to a prisoner she has captured, believing him to be one of the "Others" -- prompting Sayid to go to great lengths to learn the truth of the man's identity, and bringing up memories of his first initiation as a torturer.
When Claire's baby falls ill, she joins Rousseau and Kate on a mission to the facility where she was held after her abduction -- and remembers what happened to her during those forgotten weeks. Jack and Locke attempt to keep their prisoner a secret.
Sun debates telling her husband a personal secret that will change their lives forever. Locke enlists Ana Lucia's help in interrogating the prisoner in the hatch.
Locke is trapped with the prisoner when a lockdown protocol seals them inside the hatch. Jack attempts to win the medical supplies back from Sawyer in a game of cards, while Ana Lucia, Sayid, and Charlie discover Henry's alibi.
Hurley attempts to kick his eating addiction, only to see visions of his friend from the mental institution on the island as a result. While Libby tries to support him, while Locke and the others learn something new about their prisoner.
Bernard proposes to create an S.O.S. sign on the beach in the hopes of rescuing his wife, and is stunned when she is opposed to the plan. Meanwhile, Jack and Kate go in search of the Others to propose a prisoner exchange, and Locke faces a personal crisis.
After the prisoner attacks Ana Lucia, she is tempted to kill him and reminded of her shady past -- and working for Jack's father in Australia. When Michael returns with news of the Others' encampment, Jack and Locke prepare to attack them.
Prompted by a dream of his brother, Mr. Eko enlists Locke's help in locating a secret location on the island. Jack and the others cope with a horrible situation in the hatch after three of the survivors are found shot.
Michael prepares a small group to attack the Others' camp and rescue Walt, as he recalls his time as their captive. The group prepares to bury two of their friends.
When Desmond returns he and Locke plan to seize control of the hatch from Eko. Desmond remembers the life that brought him to the island, while Jack and Sayid come up with a plan to thwart Michael's attempt to lead the group into the Others' trap.
