SG-1 boards an abandoned Goa’uld mothership that has mysteriously arrived in Earth’s orbit, and must escape the doomed vessel when it crashes into the ocean.

Carter must find a way to save Earth from total destruction at the hands of the Goa’uld, who have turned the Stargate into a doomsday bomb. Rya’c joins his father on a mission to destroy the Goa’uld weapon.

Tragedy reunites Teal’c with his son, who blames him for the death of his mother. O’Neill and Carter launch a risky plan with untested technology when Earth comes under attack by the Goa’uld.

Palmer has had enough of Sherry’s power plays and has a final showdown with her in the hotel ballroom. Nina knows that the Drazens have no leverage without Kim, so she calls Jack and tells him that Kim’s body was found floating in the harbor. Jack is crushed by grief and then he flies into a rage. He rushes the Drazens and a bloody shoot-out ensues. Nina’s cover is blown and she makes a final dash for safety, leaving a bloody trail behind her. Jack is able to apprehend her before she can escape, but he is stunned to learn that he didn’t arrive soon enough.

SG-1 must come to the rescue of their once-powerful allies when the Goa’uld attack a secret Asgard laboratory.

The Drazens threaten to kill Kim unless Jack pays Palmer a visit. Jack complies and is able to save Palmer’s life once again. Jack then agrees to trade his life for Kim’s since the Drazens believe Palmer is dead.

Kim manages to escape from the Drazens and swims to safety.

Teri tells Jack about her unexpected good news.

A second mole is revealed inside CTU.

Daniel Jackson is exposed to a lethal dose of radiation while visiting an alien civilization that is building a weapon of mass destruction.

The Drazens contact Mason and offer to trade Jack for Alexis. Mason is reluctant, but Palmer pressures him to go ahead with the deal.

Nina and Tony try to distract Teri when they learn of Kim’s abduction.

Palmer is tempted by a member of his staff.

SG-1 must turn to a pair of convicted criminals to save a world from annihilation by the Goa’uld.

SG-1 encounters a young woman with the ability to control Replicators, and who may hold the key to the salvation of the Asgard.