With changes in leadership and new allies, the team continues to battle the Wraith and confront new existential threats. Personal dynamics shift as members struggle with loss and make significant choices that shape the fate of Atlantis and its mission in the Pegasus Galaxy.

Season 4 Episode 4 - Doppelganger

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. Air Date : 18th-Oct-2007

Season 4 Episode 1 - Adrift (2)

Floating in deep space with the city's protective shield failing, the team must do all they can to keep Atlantis alive. A radical injury threatens Dr. Weir's life. Air Date : 27th-Sep-2007  Read More

Season 4 Episode 2 - Lifeline (3)

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. Air Date : 4th-Oct-2007  Read More

Season 4 Episode 3 - Reunion

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. Air Date : 11th-Oct-2007  Read More

Season 4 Episode 4 - Doppelganger

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. Air Date : 18th-Oct-2007  Read More

Season 4 Episode 5 - Travelers

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. Air Date : 25th-Oct-2007  Read More

Season 4 Episode 6 - Tabula Rasa

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. Air Date : 1st-Nov-2007  Read More

Season 4 Episode 7 - Missing

During a visit to New Athos, Teyla and Dr. Keller find themselves on the run from a primitive tribe of warriors. Air Date : 8th-Nov-2007  Read More

Season 4 Episode 8 - The Seer

The team meets a man with extraordinary prophetic abilities, who gives them a dark prediction about Atlantis's future. The Wraith seek a new alliance with Atlantis in their war with the Replicators. Air Date : 15th-Nov-2007  Read More

Season 4 Episode 9 - Miller's Crossing

Rodney McKay goes in search of his sister on Earth after she is kidnapped by the head of a powerful corporation. Air Date : 29th-Nov-2007  Read More

Season 4 Episode 10 - This Mortal Coil (1)

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. Air Date : 6th-Dec-2007  Read More

Season 4 Episode 11 - Be All My Sins Remember'd (2)

With a plan to potentially extinguish the Replicator threat, the Atlantis team must seek an alliance with a fleet of Wraith ships. Air Date : 3rd-Jan-2008  Read More

Season 4 Episode 12 - Spoils of War

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. Air Date : 10th-Jan-2008  Read More

Season 4 Episode 13 - Quarantine

An automated lockdown traps Atlantis personnel in various parts of the city, each of them hoping the others will come to their rescue. Air Date : 17th-Jan-2008  Read More

Season 4 Episode 14 - Harmony

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. Air Date : 24th-Jan-2008  Read More

Season 4 Episode 15 - Outcast

While on personal leave on Earth, Sheppard and Ronon learn that scientists have engineered a human-form Replicator -- who is now on the loose. Air Date : 31st-Jan-2008  Read More

Season 4 Episode 16 - Trio

McKay, Carter, and Keller are trapped in an underground chamber while on an off-world mission, with no apparent means of escape. Air Date : 7th-Feb-2008  Read More

Season 4 Episode 17 - Midway

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. Air Date : 14th-Feb-2008  Read More

Season 4 Episode 18 - The Kindred (1)

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. Air Date : 21st-Feb-2008  Read More

Season 4 Episode 19 - The Kindred (2)

The team is shocked when an old friend, believed to be dead, miraculously returns to them. Teyla plans an escape from Michael's captivity. Air Date : 28th-Feb-2008  Read More

Season 4 Episode 20 - The Last Man (1)

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. Air Date : 6th-Mar-2008  Read More