Jack's decision to put a plan in action in order to set things right on the island is met with some strong resistance by those close to him, and Locke assigns Ben a difficult task.

Jack's decision to put a plan in action in order to set things right on the island is met with some strong resistance by those close to him, and Locke assigns Ben a difficult task.

Richard Alpert's back story is shown: In 1867, he is brought to the island on the Black Rock as a slave. He makes a deal with Jacob to be his representative in exchange for immortality. In the present day, Hurley convinces him to help the candidates replace Jacob and stop the Man in Black from leaving the Island.

Jacob and the Man in Black are revealed to be twin brothers. They are raised by a mysterious woman who is charged with protecting the island. As revenge for the murder of their adoptive mother (who killed their real mother), Jacob throws his brother into the source of electromagnetism after being made the island's guardian, which transforms the Man in Black into the smoke monster.