The season continues the stories of the survivors of the fictional crash of Oceanic Airlines Flight 815. Ben, Sun, Ilana and Frank remain fixed in time upon their return to the island, but Jack, Kate, Hurley and Sayid are flashed back in time to 1977, where they are reunited with Sawyer and Juliet. Meanwhile, Miles';; colleague Daniel Faraday embarks on a time-traveling mission that introduces him to a nuclear bomb named Jughead and a young woman named Ellie.
