SGA Season Four Episode Guide

EPISODE #: 401 AIR DATE: 09.28.07



Floating in deep space with the city's protective shield failing, the team must do all they can to keep Atlantis alive. Meanwhile, a radical injury threatens Dr. Weir's life.

EPISODE #: 402 AIR DATE: 10.05.07




Colonel Sheppard and his team embark on a risky mission to steal a Z.P.M. power module from the Replicators – but must rely on a compromised Dr. Weir to succeed.

EPISODE #: 403 AIR DATE: 10.12.07



When a group of Ronon's people enlist the team's help in raiding a Wraith weapons facility, Ronon reconsiders whether his future lies in Atlantis or with his friends.

EPISODE #: 404 AIR DATE: 10.19.07



During an off-world mission Colonel Sheppard unknowingly becomes host to an alien entity, which infects others in Atlantis and afflicts them with terrifying nightmares.

EPISODE #: 405 AIR DATE: 10.26.07



Colonel Sheppard is captured by the inhabitants of a generational ship and their beautiful leader, who wish to use his ability to use Ancient technology for their own ends.

EPISODE #: 406 AIR DATE: 11.02.07



When a virus causes amnesia in everyone except Teyla and Ronon, the Atlantis team must work together to find a cure before their memories fade entirely.

EPISODE #: 407 AIR DATE: 11.09.07


During a visit to New Athos, Teyla and Dr. Keller find themselves on the run from a primitive tribe of warriors.

EPISODE #: 408 AIR DATE: 11.16.07



The team meets a man with extraordinary prophetic abilities, who gives them a dark prediction about Atlantis's future. Meanwhile, the Wraith seek a new alliance with Atlantis in their war with the Replicators.

EPISODE #: 409 AIR DATE: 11.30.07


Rodney McKay goes in search of his sister on Earth after she is kidnapped by the head of a powerful corporation.

EPISODE #: 410 AIR DATE: 12.07.07



A mysterious drone crashes into Atlantis, indicating that the Replicators may have found the city. But when Elizabeth Weir appears, the team realizes that the probe is just a part of a bigger mystery.

EPISODE #: 411 AIR DATE: 01.04.08




With a plan to potentially extinguish the Replicator threat, the Atlantis team must seek an alliance with a fleet of Wraith ships.

EPISODE #: 412 AIR DATE: 01.11.08



The team finds their former Wraith ally's hive ship drifting in space, which leads them to a secret project that could turn the tide of a civil war.

EPISODE #: 413 AIR DATE: 01.18.08


An automated lockdown traps Atlantis personnel in various parts of the city, each of them hoping the others will come to their rescue.

EPISODE #: 414 AIR DATE: 01.25.08


Colonel Sheppard and Dr. McKay must protect a child princess on a pilgrimage before she can become queen, and learn that she has dangerous enemies threatening her life.

EPISODE #: 415 AIR DATE: 02.01.08


While on personal leave on Earth, Sheppard and Ronon learn that scientists have engineered a human-form Replicator – who is now on the loose.

EPISODE #: 416 AIR DATE: 02.08.08



McKay, Carter, and Keller are trapped in an underground chamber while on an off-world mission, with no apparent means of escape.

EPISODE #: 417 AIR DATE: 02.15.08




Teal'c visits Atlantis to counsel a headstrong Ronon, who is up for review by the I.O.A. But the two must work together when the Wraith invade the Midway space station in order to reach Earth.

EPISODE #: 418 AIR DATE: 02.22.08


As a mysterious new illness sweeps through the Pegasus Galaxy, Teyla is convinced by a vision that the father of her child is trying to communicate with her.

EPISODE #: 419 AIR DATE: 02.29.08



The team is shocked when an old friend, believed to be dead, miraculously returns to them. Teyla plans an escape from Michael's captivity.

EPISODE #: 420 AIR DATE: 03.07.08



Sheppard returns to Atlantis after a mission and finds the city abandoned, all systems dead – and instead of ocean, sand dunes as far as the eye can see.