SG-1 travels to a dark world where they are attacked by primitive creatures, but scare them off with gunfire. They then come across a group of people who are rescuing one of their own from the cavemen, who are thought to be cursed and referred to as "The Touched". They find that the planet has a light side where a Minotian (bull statues abound) culture lives. After a bit of discussion about the Touched, SG-1 returns home. Shortly thereafter, members of the team demonstrate violent behavior, causing a lockdown when Dr. Fraiser discovers that they brought back some sort of parasite. This parasite causes anyone infected to revert to violent primitive behavior, loss of speech ability, increased hair growth, and a thickening brow.
After further investigation, Daniel and Teal'c are found to be immune, as well as Dr. Fraiser. Daniel and Teal'c are sent back through the gate to obtain blood samples from the Untouched to try and determine why they aren't infected. Along the way, Daniel is captured by the Touched, while Teal'c tries to get blood from the Untouched. They are in no hurry to give up their blood, so they demand he leave. He successfully obtains a blood sample by knocking out two guards on his way out.
With the fresh blood samples, Dr. Fraiser discovers that the parasite is histamine-based, and due to her and Daniel taking strong anti-histamine medicine, they are able to avoid the parasite's effects. Everyone receives anti-histamine shots and is cured. They then return to the planet with anti-histamine loaded tranquilizer guns and return the Touched to normal and retrieve Daniel, who had turned primitive once his medicine wore off. Happy reunions occur between the Untouched and their loved ones who they thought were lost to the curse.
First appearance of Dr. Janet Fraiser and Colonel Makepeace.
Tropes specific to this episode include:
- Artistic License – Medicine: Dr. Frasier refers to the alien organism causing the disease as "like a parasitic virus". Viruses are parasitic by definition. This might be put down to how she was under a lot of stress and trying to give a summary of her findings without a clear term for what she had found. Completely averted with the drug used to clear the body of histamine (to starve out the organism): Dr. Frasier refers to Chlorpheniramine Maleate
, which is an actual antihistamine that does exactly what she says. - Call-Back: The prologue references the events of the pilot: the gate address of the planet of the week was found by trying to match the symbol combination of Apophis, Amaunet/Sha're, and Klorel/Skaara's destination to their as-yet incomplete database of gate addresses based on the Abydos cartouche.
- Chekhov's Gun: Daniel's allergies turn out to be important to the plot when they're revealed to be the reason for his immunity to the Touched virus.
- Chick Magnet: Lampshaded by O'Neill when the rest of the team finds Daniel getting cozy with Melosha after succumbing to the disease.O'Neill: Daniel, you dog. Keep this up, you'll have a girl on every planet.
- Clothing Damage: Daniel's clothes are pretty well shredded once he's recovered from the dark side of the planet.
- Contamination Situation: The majority of the SGC staff rapidly succumb to the virus, with Fraiser running out of space to quarantine them all.
- Early-Installment Weirdness:
- In this episode, SG-1 are in full dress uniforms during their mission briefing. In subsequent episodes, the mission briefings are less formal and they just wear their fatigues.
- Fraiser also refers to Teal'c as Mister Teal'c repeatedly, rather than just Teal'c.
- Forceful Kiss: Carter attempts to force herself on O'Neill after coming down with the parasite; Fraiser explains that this is because primitive females would usually seek to mate with the strongest male of the group.
- Goggles Do Something Unusual: The 'thermal night vision goggles' worn by the team.Jack: Hey, here's an idea: why doesn't the MALP have a set of these?
- He's Back!: Said by O'Neill when Daniel recovers from the virus and immediately starts complaining that they haven't come up with a better name for the planet of the week than its military designation.
- The Immune: Daniel and Fraiser, due to their regular intake of strong antihistamines to combat their allergies, and the Untouched, who apparently have low histamine levels because of their diet. Teal'c is also resistant to the parasite, but in his case it's because of his symbiote.
- Interservice Rivalry: A mild case between the marines of SG-3 and the air force personnel.
- Just a Flesh Wound: Fraiser informs Teal'c that Carter was stabbed by her roommate while in quarantine, then hastily reassures him that the damage was 'superficial'.
- No-Holds-Barred Beatdown: O'Neill delivers one to Daniel while suffering the effects of the virus.
- No Ontological Inertia: The physical changes wrought by the parasite quickly go away once it is cured.
- The Plague: The entire premise of the episode.
- Pop-Cultural Osmosis Failure: Teal'c, again:O'Neill: Lucy, I'm home!
Teal'c: I am not Lucy. - Tidally Locked Planet: The Planet of the Week is tidally locked with its sun so one side is always light, the other always in darkness. The civilization lives in the light side near the terminator, where it is temperate. The gate is in the darker areas of the terminator.
- Title Drop:Daniel: What better opportunity to study the Broca Divide?
