Within the ruins of the legendary city of Atlantis is buried a secret base left by the Ancients, originators of the Stargate. A new team of explorers travel to the distant galaxy where Atlantis is located, where a primitive human civilization is threatened by a sinister enemy.
The action-packed sci-fi drama returns for its third series, as the Atlantis' crew desperately tries to stop two Wraith hive ships from reaching Earth. (S3, ep 1)
A dangerous situation develops when the Atlantis team set up a prisoner of war camp for former Wraiths. Meanwhile, the IOA continues its investigation into Dr Weir. (S3, ep 2)
The Atlantis team needlessly risk their lives when they find themselves in the thrall of an obnoxious, but mysteriously powerful, man. (S3, ep 3)
Ronon Dex is captured by the Wraith and returned to his homeworld, where he is haunted by his past as he is forced to once again become their prey. (S3, ep 4)
Weir and the team visit an advanced civilisation that split off from the Lanteans thousands of years ago, but discover that they may not have left Atlantis in peace. (S3, ep 5)
Elizabeth Weir wakes up in a mental institution, where she is told that the expedition to Atlantis and the Stargate are figments of her imagination. (S3, ep 6)
Colonel Sheppard finds himself the prisoner of a renegade Genii warrior, along with a Wraith who has been separated from his hive. (S3, ep 7)
McKay And Mrs Miller: McKay is reunited with his estranged sister, who gave up a promising career to raise a family. Will she put their differences aside to help the SG-1 team? (S3, ep 8)
While on a mission to rescue a lost team, Sheppard and Ronon are placed in serious danger when they are influenced by a mind-altering device created by the Wraith. (S3, ep 9)
The Return (Part 1): The Atlantis expedition is stunned to learn that a ship of Ancients is returning to reclaim their lost city. Guest starring Richard Dean Anderson. (S3, ep 10)
The Return (Part 2): The team goes against orders to launch a rescue attempt to free General Jack O'Neill, so that they can try to save Atlantis from Replicator control. (S3, ep 11)
When the people of Atlantis begin to have ghostly visions, Teyla believes the apparitions they are seeing are actually Ancients, warning them of a great danger. (S3, ep 12)
When the team finds Lucius up to his old tricks again they try to blow the whistle on his scamming ways, but are drawn into a fight with Kolya and his men. (S3, ep 13)
Zapped by a mysterious device left running by the Ancients, Rodney McKay (David Hewlett) begins to evolve into a super human. (S3, ep 14)
Upon realising that a simulation game they have been playing is real, McKay and Sheppard are forced to put their petty squabbles aside. (S3, ep 15)
After discovering an antiquated space station, Sheppard and his team mistakenly awaken a race of people who have been frozen in stasis for thousands of years. (S3, ep 16)
The Atlantis team unwinds during a city wide holiday, but their rest and relaxation is cut short when a deadly explosion rips through the city. (S3, ep 17)
While searching for a geothermal drilling station on the ocean floor, the team unknowingly awakens a Wraith queen who has lain dormant for thousands of years. (S3, ep 18)
While investigating a village that had previously gone missing, Sheppard and his team stumble onto a Wraith experiment built to create large, deadly insects. (S3, ep 19)
A failed attack on a Replicator armada forces McKay to follow in the footsteps of the Ancients and take a drastic step to save Atlantis from destruction. (S3, ep 20)