Enemies (S05E01)

After losing Teal'c to Apophis (in the previous episode, Exodus), O'Neill, Carter, Daniel and Jacob find themselves aboard Cronus' ship stranded in a remote part of the galaxy. As they are about to do battle with Apophis', a mysterious third ship appears, attacking their foe. This gives them the opportunity to escape, but Cronus' ship has sustained serious damage to its control crystals and is not operating at full capacity. Back at SGC, Hammond receives news that the Tok'ra Council believes SG-1 and Jacob were killed in the massive explosion that destroyed Apophis' fleet. But Hammond's not ready to write off SG-1 so easily. Apophis' ship eventually catches up to SG-1's ship, but sensors reveal there are no apparent signs of life there. With a plan to obtain control crystals, SG-1 transports onto Apophis' ship. There they find many dead Jaffa as well as a programmed auto-destruct sequence in progress. Most astonishing is the reason for the ships' state: it's infested with an army of replicator bugs, courtesy of the mysterious third ship. SG-1 narrowly escapes the bugs and the auto-destruct, making it back to their own ship. But no sooner do they arrive than a cargo ship appears on the sensors. They are overjoyed to see that it's piloted by Teal'c: he had somehow escaped death on Apophis' ship before it blew up. SG-1 rushes to meet him, only to find that he is in the company of Apophis, and that their biggest battle is about to take place. (Metro-Goldwyn-Mayer (MGM))