“The Tok’ra: Part 1” is episode eleven of season two of Stargate SG-1.
In the episode “In the Line of Duty”, Captain Carter was possessed by a Goa’uld, one of the Tok’ra, opponents of the Goa’uld System Lords. Sam’s father, General Jake Carter was introduced in “Secrets”, and he revealed he had terminal cancer.
Although the Tok’ra possessing her had died, Sam has continued to get glimpses and visions from its memory. Now, she has seen a gate address for a Tok’ra world.
The team go through and find the Tok’ra and propose an alliance, but some of them are not too happy, as when Apophis’ pyramid ships were destroyed in the attack on Earth in “The Serpent’s Lair”, some members of the Tok’ra were killed. Admittedly, it’s hard for the Tok’ra to maintain their numbers, as they only seek willing hosts, but it seems a bit churlish to object to Earth defending itself from destruction at the hands of the same System Lords the Tok’ra are opposed to.
The Tok’ra only take hosts who volunteer, in a symbiotic manner, unlike the Goa’uld who take hosts by force. Their hosts benefit from the Tok’ra’s healing powers (they refuse to use the healing sarcophagi like the Goa’uld, believing that long term use is corrupting). Guess where that is leading?