Season Four

O'Neill and Teal'c risk their lives to keep the Replicator bugs from gaining a foothold on Earth, while Carter helps the Asgard fend off a Replicator invasion.

A warring alien race offers to exchange their advanced technology for Earth's help in defeating their enemy.

A Tok'ra archaeologist arrives at the S.G.C. with newly discovered technology, giving the SG-1 team superhuman powers.

Teal'c is reunited with his lost love – a woman who claims to have found a way to communicate with her symbiote and defeat the Goa'uld.

When a member of the S.G.C. tries to kill a Tok'ra, it is revealed that O'Neill and Carter may be victims of an untraceable form of Goa'uld mind control.

O'Neill and Teal'c are caught in a time loop in the S.G.C., and must relive the same 10 hours over and over again.

The Russians recover a Stargate from the bottom of the ocean, and turn to the S.G.C. for help when their experiments go awry.

After Dr. Jackson is taken captive by an Unas while on an archaeological dig, the S.G.C. mounts a rescue operation – but discovers a danger of their own.

SG-1 is caught in a conflict between two civilizations trying to colonize the same planet.

The members of SG-1 are used as forced labor in an underground alien facility after their memories are erased by the ruling elite.

SG-1 investigates a conspiracy theorist who has detailed knowledge of the Stargate program.

A test gone wrong leaves Jack and Teal'c marooned in space aboard a damaged prototype attack ship.

When his former mentor dies, Dr. Jackson returns to his roots – and discovers an ancient Egyptian artifact containing a Goa'uld parasite.

SG-1 must stop Apophis and Heru'ur from forming an alliance of their powerful forces, while Teal'c is captured and tortured by the Goa'uld.

SG-1 must adjust to a new commanding officer when General Hammond steps down – but O'Neill discovers foul play behind the general's resignation.

Ten years into the future, the former members of SG-1 must send a message into the past to prevent the extinction of the human race.

Jackson's teammates notice a disturbing change in him when he is reunited with the Harcesis child and given the Goa'uld genetic memory.

SG-1 finds a deserted Goa'uld palace, where a beautiful device causes suicidal tendencies.

Carter must help keep a promising young cadet from throwing away a future at the S.G.C. O'Neill and Teal'c encounter a dangerous life form at an offworld research base.

The S.G.C. is invaded by an alien life force that takes up residence in the base computer system – and in Major Carter.

SG-1 joins forces with their robot doubles to rescue an alien world from the Goa'uld Cronus, while Teal'c seeks revenge for the murder of his father.

SG-1 helps to evacuate the Tok'ra to a new base – but matters are complicated when a spy reveals their location to Apophis. The team attempts a daring plan to take out the Goa'uld's powerful fleet.