The Enemy Within

"That's right Dorothy, it was all a dream."

- Jack O'Neill

"The Enemy Within" is the third episode of the first season of Stargate SG-1.

Plot
In the previous episode, Major Charles Kawalsky was infested by a Goa'uld without anyone noticing. The Goa'uld had remained fairly dormant in him for a while due to its youth, but as it matures it begins to take control of Kawalsky, causing him to experience blackouts, during which the Goa'uld takes over his body. During one blackout he kills a doctor who had discovered the symbiote, and stands before the Stargate without doing anything. In the meantime, Teal'c, who had recently come to the SGC, is questioned by Colonel Kennedy of the Pentagon. He does not know the answers to their questions because the Goa'uld's technology is considered magic. However, he can tell them what he knows of Goa'uld culture. They rule by fear, and kill any who do not serve them. He also says there are a few like Apophis (the System Lords) who rule over many planets, but they would not be interested in peace. Many worlds fend for themselves and when they meet the Goa'uld, they are enslaved. It would take months for the Goa'uld to make ships to attack Earth since its impenetrable iris prevents invasion through the Stargate. The Goa'uld are few in number but strong and growing. He knew of a human race where everything started, the Tau'ri, the First Ones. Some became hosts, others became Jaffa and slaves. Yet their world was forgotten for centuries. Colonel O'Neill stated that the Tau'ri are the people of Earth, the ones who sealed the Stargate. Now many worlds out there are seeded with the ancient peoples of Earth. Teal'c felt the Tau'ri are their best hope. The high-ranking officers decide to bring him to Washington.

Once the SGC discovers that Kawalsky has a Goa'uld in him, they call upon the expertise of some medical experts for an attempt to remove the Goa'uld. Dr. Warner discovers that it is wrapped tightly around his spinal cord, and removing it could either kill or paralyze Kawalsky. Teal'c also informs them that the Goa'uld will kill its host if attempts are made to remove it from him. As such, a suitable sedative must be found and applied to the symbiote before operation can begin.

Teal'c reveals that every Goa'uld has the genetic memory of those before it. Kennedy suggested convincing the symbiote to share that knowledge. However, the Goa'uld view them as an inferior race and would not have told them anything.

Teal'c allows medical staff to perform controlled experiments on the larval Goa'uld that acts as his immune system until they find an effective sedative. They then use this and begin work on Major Kawalsky, who makes General Hammond promise that he'll kill him if the Goa'uld wins the battle for his body.

The operation appears to be successful. Afterwards, he requests a few moments with Teal'c alone to thank him for his help, but as soon as they are alone, Kawalsky's eyes glow and he grabs Teal'c by the neck. The Goa'uld, though mostly removed, had already bound itself irreversibly to the host's brain and is in full control - Kawalsky had been dead for hours.

Overpowering Teal'c, the possessed Kawalsky attempts an escape through the Stargate, only to find Teal'c standing on the ramp blocking his path. They fight and struggle while O'Neill and Hammond try to shut down the Stargate. The Goa'uld pushes the struggle right up to the Stargate, and gets partially through it before the device shuts off, slicing off the back of Kawalsky's head, killing the symbiote instantly.

Although tragic, these events also proved Teal'c worth, allegiance and honor to the SGC, and he is thus assigned as the fourth member of SG-1 by O'Neill's recommendation.

Notable Quotes
Jackson: So this iris is gonna hold, right?

Carter: Pure titanium less than three micrometers from the event horizon. It won't even allow matter to fully reintegrate.

O'Neill: So this iris is gonna hold, right?

Carter: If it doesn't, the fail-safe device will detonate, this whole mountain will vaporize and there'll be nothing to worry about.

O'Neill: Ah, good! I feel much better.

Teal'c: I will pledge my allegiance to this world.

O'Neill: I'm just not sure that's ever going to be enough for them to trust you. To be honest with you, I think they're scared of you.

Teal'c: I understand.

O'Neill: You must be used to that by now, huh?

Teal'c: I am a Jaffa. I have served as a warrior for your enemy. I have carried your enemy within me.

O'Neill: Yeah. Well it's kind of a human thing. We tend to be afraid of things we don't know.

Teal'c: Why is O'Neill not afraid?

O'Neill: Teal'c, I saw you stand up to a god. Refuse to kill. I saw you make that decision.

Teal'c: Yes.

O'Neill: In that moment I learned everything I needed to know to trust you.

O'Neill: Permission to barge in, sir?

O'Neill: Listen, I gotta ask you something. It's not easy for me.

Kawalsky: We're friends.

O'Neill: If you don't make it... can I have your stereo?

Background notes

 * At the end of the episode, Carter says, as SG-1 enters the gate, that "the MALP reports conditions on the planet are favorable." This marks the first time the word "MALP" is uttered in the series.
 * This is the first episode in which the people of Earth are identified as the Tau'ri.
 * Up to the point where Kawalsky is being restrained in the infirmary, the centre part of Teal'c's Apophis symbol on his forehead is upside-down.
 * This episode shares its name with a Star Trek episode
 * The same name was also given to the 1996 Doctor Who TV Movie by producers as a story name "if they really want to have one", other from just "the TV Movie".

Goofs

 * Continuity: The clock differs in time (sometimes going backwards) as Major Charles Kawalsky's surgery progresses.
 * Continuity: When Teal'c is first questioned by Col.Kennedy, his tattoo/branding is with the opening of the arch facing upward. When confronted by Col. Kennedy to verify his symbiote is still in his symbiotic sack, Teal'c has his tattoo/branding upside down with the opening facing downward.
 * Continuity: The Goa'uld infesting Major Kawalsky somehow retains control of Kawalsky even after its body is removed from his. In later episodes, this is not possible. It is also possible that somehow, the "head" of the symbiote had somehow connected to the bloodstream and maintained control in the brain alone.  In later episodes, it is uncommon for the symbiotes not to be fully removed if it is at all especially by the Tok'ra, especially immature Goa'uld.
 * Factual errors: The second doctor ordered an MRI; however, the machine used was a CT (CAT) scan.

In other languages

 * Hungarian: Az ellenség karmaiban
 * Czech: 	Nepřítel je uvnitř
 * Italian: L'invasione
 * German: Der Feind in seinem Körper
 * French: L'Ennemi intérieur
 * Spanish: El Enemigo Interior
 * Portuguese: Carregando O Inimigo
 * Russian: Внутренний враг (Vnutrennyij vrag)
 * Romanian: Inamicul de Dinauntru