“Exodus” is episode twenty-two of season four of Stargate SG-1 and the season finale.
In the previous episode, “Double Jeopardy”, SG-1 – and their android duplicates from “Tin Man”, killed the Goa’uld System Lord Kronos and took control of his mothership. They bring the mothership to the Tok’ra, to lend it to them so that they can relocate the stargate.
The Goa’uld infiltrator, Tanith, from the episode “Crossroads”, has now outlived his usefulness. Of course, he isn’t simply killed, and causes problems by calling Apophis. The ships seem to be getting much faster than they used to be – once it was reported that it would take years for a Goa’uld fleet to arrive (it didn’t as it happens, as one arrived much quicker than that in “Within The Serpent’s Grasp”) but now it seems to be only taking days or weeks at most to travel between systems.
Sam comes up with an idea for destroying a good chunk of Apophis’ fleet.
The story doesn’t conclude in this episode bu continues in the first episode of season five, “Enemies”.