"Lifeline" is the second episode of the fourth season, and the 62nd episode overall, of the science fiction television series Stargate Atlantis. The episode first aired in the United States on October 5, 2007, on the Sci Fi Channel, and subsequently aired October 16 on Sky One in the United Kingdom. It was written by executive producer Carl Binder, and directed by Martin Wood. The episode is a continuation of the previous episode, "Adrift", following Colonel Sheppard and his team as they perform a mission to steal a Zero Point Module from the Asurans. It was described by executive producer Joseph Mallozzi as a "big op eppy."