Flight 815 is shown successfully landing in Los Angeles with no crash on the island, but the survivors are simultaneously shown still on the island after Juliet detonates the bomb.

The man impersonating John Locke reveals his true intentions.

Sayid miraculously comes back to life, but his problems have only just begun. Sawyer escapes, and Kate and Jin go after him. Back in Los Angeles, fugitive Kate helps Claire as she goes into labor.

On the island, the being now occupying Locke's body turns to Sawyer and promises to tell him why he's on the island. Back in Los Angeles, Locke loses his job and encounters a number of familiar faces.

Jacob sends Hurley on a mission across the island, but Jack must accompany him. In Los Angeles, Jack's difficult relationship with his son is revealed. Meanwhile, Jin discovers that Claire thinks the people at the temple stole her son.

Claire arrives at the temple and warns the inhabitants that the being inhabiting Locke wants to talk, but Dogen sends Sayid to kill him instead. In Los Angeles, Sayid saves his brother, who is in trouble with a loan shark.

Ilana prepares to kill Ben after Miles reveals that Ben killed Jacob. In Los Angeles, Ben contemplates a power play at his high school. Meanwhile, Richard and Jack share their secrets and experiences with Jacob and form an alliance.

Locke sends Sawyer on a recon mission to the other island, where he runs into Charles Widmore and his submarine crew. In Los Angeles, Sawyer works as a police officer obsessed with finding the conman who destroyed his family.

The mysteries behind Richard Alpert's arrival to the island, his immortality, and his alliance with Jacob are revealed--plus more details about the purpose of the island and the relationship between Jacob and the smoke monster.

Sun and Jin's search for each other is interrupted when Widmore's crew kidnaps Jin, and Locke heads to the other island to bring him back. In Los Angeles, Jin's job for Sun's father is sidetracked when his money is taken at customs.

Charles Widmore brings Desmond back to the island so that he can conduct a dangerous electromagnetic experiment, which sends him back to the alternate reality in Los Angeles, a reality where he has never met Penny.

Michael appears to Hurley and gives him a new mission, and Sayid captures Desmond and sends him to Locke. In Los Angeles, Desmond sets up a meeting between Libby and Hurley to further his assignment.

As the battle between Locke and Widmore commences, Sawyer launches his plan to change allegiances. Back in Los Angeles, fate continues to intervene and bring the original survivors together.

With Jack's help, Locke rescues the candidates from Widmore's compound, but their plans for leaving the island are forced to change. In Los Angeles, Jack tries to convince Locke to try an experimental surgery for his paralysis.

The story of how Jacob and his brother came to the island, their uneasy relationship with their "mother," their eventual falling-out, and revelation of what Jacob was on the island to protect.

Jacob appears to the survivors of the submarine explosion and tells them what they were chosen for. Ben joins forces with Locke, as they both have a final showdown with Charles Widmore.

The Man in Black searches for Desmond to achieve his goal of destroying the island. Jack, the newly-appointed "protector" of the island, sets out to stop him. In Los Angeles, the survivors reunite and recall their island experiences.