Locke, Sayid, and Kate encounter the Others' homes for the first time and find Jack relatively happy amongst them. Jack and Juliet, whose relationship has advanced, have cut a deal with Ben to leave the island on the Others' submarine, but Locke blows it up. Ben reveals that he has Locke's father in captivity. In flashbacks, Locke's father pushes him out of a window, which paralyzes Locke.
(From Wikipedia)
