An alien artifact transports Daniel to an alternate reality, where he is not a part of the Stargate program and the Goa'uld -- led by Teal'c -- are invading Earth.

Carter is possessed by a Goa'uld who claims to be an enemy of the System Lords.

SG-1 is put on trial and exiled to a prison world, where a woman maintains a strange control over her fellow prisoners.

SG-1 is imprisoned in a virtual reality realm and forced to relive the worst moments of their lives over and over.

SG-1 returns to Cimmeria, and finds that without protection from the Asgard the planet has been invaded by the Goa'uld.

The SG-1 team attempt to rescue Teal'c's son, who has been kidnapped and brainwashed by Apophis. Teal'c learns disturbing news about his wife.

Teal'c is infected with deadly venom from a giant insect, and begins a terrible transformation. When he escapes the S.G.C., SG-1 must find him before Colonel Maybourne does.

SG-1 locates the Tok'ra, a Goa'uld resistance movement who oppose the System Lords, and attempt to form an alliance. Jacob Carter's cancer brings him near death.

While SG-1 tries to form an alliance with the Tok'ra, a spy betrays the rebels to the Goa'uld. Jacob Carter finds that the Tok'ra may be his only hope of survival

SG-1 finds a planet inhabited by Native American Indians, protected by spirits who are actually advanced alien shapeshifters.

The Asgard aid Earth in negotiating a nonagression treaty with the Goa'uld System Lords.