Out of the blackness, the first thing Jack senses is pain. Then burning sun. A Bamboo forest. Smoke. Screams. With a rush comes the horrible awareness that the plane he was on tore apart in mid-air and crashed on a Pacific island. From there it's a blur, as his doctor's instinct kicks in: people need his help.

Jack and Hurley discover an alarming secret about Kate, as the marshal's life hangs in the balance. Meanwhile Kate, Charlie, Sawyer, Sayid, Boone and Shannon ponder the island's mysteries they've uncovered and worry that telling the other survivors will cause panic, and Locke's befriending of Walt disturbs Michael.