The SG-1 Team are evacuating the Nassian people from their camp through the Stargate as they're under attack by the Goa'uld. Carter stops to help a dying Nassian and as she starts giving him mouth to mouth, something - we don't see what - goes into her mouth. With blood on her mouth she turns away and...her eyes glow. O'Neill comes back for her and she tells him she's fine, explaining the blood is from where the man bit his tongue as he died. They go back through the Stargate.

Carter undergoes the usual after mission check-up and Dr Fraiser finds a slight abrasion at the back of her throat from which she takes a swab. Carter explains that she's had a sore throat lately. Janet mentions that Cassie will be at the hospital where the overflow of Nassians are being treated the next day, and maybe she'd like to come and see her.

At the hospital one of the Nassians is badly burnt - covered head to toe in bandages - but amazingly shows no sign of infection. Even more amazingly he's not dead, and when he's left alone we see that his stomach glows.

Sam visits Cassie who hugs her, then immediately pulls away staring at her in horror. Running to the other side of the room she hides behind the couch. Sam's eyes glow as she walks towards the young girl...

O'Neill is summoned to the hospital by Fraiser who tells him that Cassie will only speak to him about whatever has happened. Cassie reveals that Sam said she would kill her if she told anyone. Jack finds that hard to believe; that Sam wouldn't do that. "She would now," Cassie tells him. "She's a Goa'uld."

At the SGC Carter is stomping around demanding to know where the Colonel is, obviously desperate to get through the Stargate. O'Neill meets them in the gate room, and when Carter's distracted he injects her with enough sedative to take down an elephant. Naturally, nothing happens. Lifting her gun she points it at him and the Gao'uld commands that he open the Stargate.

A guard shoots her with a drugged dart, but again it has no effect. Jack tries to tackle her but she throws him to the floor and pulls the pin out of a grenade. He tells her again that no one's going to let her through the Stargate...she pleads once more...then passes out. Jack manages to grab the grenade and re-inserts the pin.

In the briefing room Fraiser explains that Cassie still has Naqadah - the Stargate material - in her bloodstream, which probably explains why she could sense the Goa'uld. She also states that if it's possible for a Goa'uld to enter a host without any physical signs of entry, then everyone who comes back through the Stargate is going to have to have x-rays and a MRI.

Then Jack remembers - on the planet she was giving that Nassian mouth to mouth and she had blood on her mouth. That's how it must have got in.

Teal'c is concerned that the Goa'uld may have already planted bombs around the SGC, so Hammond asks him to help them search for any using his specialised knowledge.

Daniel asks what they're going to do about Carter. Jack insists that they're going to get that thing the hell out of her but Daniel reminds him that it didn't work very well with Kawalsky. Hammond orders Jack to question the prisoner, even though Jack himself doesn't think it's a very good idea.

In the locker room Jack is sitting next to Carter's locker looking distraught (I was squealing at this point). Teal'c quietly enters and sits next to him, sensing the mood. He tells O'Neill he knows it is difficult, but gives him some advice to attack the Goa'uld's ego. As Jack leaves Teal'c tells him that when he speaks to her, he should not see her as his friend. Jack doesn't know how to do that.

At the hospital, Daniel locates the wife of the man Carter gave mouth to mouth to. She recalls no unusual activity - no glowing eyes, no strange behaviour - of late, only that several months ago he had a scar on his neck. In another room a Doctor lies unconscious on the floor and the heavily burnt man pulls off his own bandages. He is no longer burnt. Coughing up a metal object (I'll just take a moment here to say "Ick!") that fits on his hand, he puts it on and we can see that the energy from three crystals on the object join together.

Frasier comes back in the room, checks on the man covered in bandages, and leaves.

Teal'c talks with the Goa'uld, who tells him that it's name is Jolinar and that it is a Tok'ra - part of a rebel group of Goa'uld who fight and oppose the System Lords. They share this information with Jack, but there's no way to prove it ("Unfortunately we do not carry identification."). Jolinar claims that they do not enter people unwillingly, only those who are dying. Jack points out that it killed the Nassian man when it left the body; Jolinar disagrees. It left the Nassian man because he was already dead. Carter was a desperate choice.

Back at the hospital the previously burnt man (now known as the baddie) has disguised himself as a Doctor and is using the device on his hand to search patients for any sign of Goa'uld activity. Frasier gets the latest blood work on the bandaged patient. Realise something's wrong she pulls the bandages off his face...it's the Doctor who went missing.

Jolinar knows that the baddie is an assassin who the System Lords have sent to kill it. Despite O'Neill and Teal'c's assurances, it knows that the assassin will get into the SGC - it's what it does.

Jolinar is right. Having no luck at the hospital, the assassin dresses up as an army office and gets into the SGC quite easily by using the device on its hand to control people. Finding the brig it kills the two guards there and then starts using the device on a defiant Sam/Jolinar...

Hammond gets a call from the infirmary - there's an officer there who has no memory at all of driving to the SGC. Seeing that the security camera in the brig is off, Jack and Teal'c run down there.

In the brig the assassin is looking over Sam's still body. Two more guards burst in. "She's dead." He tells them, then orders them to leave with him.

Jack and Teal'c burst into the brig. As Teal'c studies the two guards and determines they're dead, Jack rushes over to Carter. He tells Teal'c to get a medical team and touches her face. "Sam? Sam!"

Sam is wheeled into the infirmary and Fraiser's diagnosis is that the Goa'uld is dying and taking Carter with it. Daniel sees the last of the Nassians off through the Stargate as they leave for a new camp, then turns to see the assassin enter the gate room. He recognises him from the hospital but the assassin grabs him and holds him hostage, demanding that they send him through the Stargate.

Hearing the intruder alert in the infirmary O'Neill tells Teal'c to go. Teal'c - being Teal'c - soon sorts it all out. Walking into the gate room he apologises to Daniel then shoots both Daniel and the assassin with the zat gun. Once they are separated, Teal'c shoots the assassin a second time, killing him.

The Goa'uld dies and Carter is getting worse...then gets better. Relieved, Jack congratulates her when she wakes telling her that she beat it, but he's wrong. The Goa'uld gave up it's life so that she could live.

REVIEW:

I don't know if I can give an exact reason why this episode works for me. It's certainly not the best episode ever. It's not the funniest, most dramatic, best character piece, best relationship portrayal, most action packed episode there is...it just seems to work. Maybe because there's so much of everything in there.

It's a great Amanda Tapping episode without being about the fact that she's a woman, which is fabulous. She gets to be ominous yet kind (how that works I have no idea).

It's a great O'Neill/Teal'c friendship episode. When Jack's worried about Sam, Teal'c is the one to come and see him, to offer him comfort along with advice. Nice.

It's a great Jack/Sam relationshipper episode. When he's been ordered to question Sam...and he's sitting in the locker room, intentionally within view of her locker, obviously finding this very hard...and then Teal'c comes in and talks to him quietly.

I love it. No glib responses, no smart-ass comments. Jack is quiet, subdued, and concerned. Love it.

Best of all...when they find her unconscious and she's wheeled into the infirmary, I swear to GOD he wipes away a tear. It's not very subtle, either. And when they hear there's an intruder Jack doesn't move from her side - he just tells Teal'c to go and stays where he is. Bless!

Other fun bits: Teal'c using the zat gun. "I am sorry Daniel Jackson." Michael Shanks' reaction is fab, as is his "Oh geez," when the assassin holds him hostage.

And I love, absolutely love, the scene near the end when Daniel goes to visit Sam. He brings her flowers, sits on the edge of her bed and says "Hi Sam. How are you doing today?"

She doesn't reply. I love that.

Another bonus for this episode is the continuity. The events in this episode will be important for years to come...fab.

BEST LINES:

Daniel: "What about Carter?"
Jack: "We're going to get that damn thing out of her, that's what we're gonna do!"

Teal'c: "This is difficult."
Jack: "Yeah. Yeah it is."

Teal'c: "When you speak to her, do not see your friend."
Jack: "How do you do that?"

Jack: "Sam? Sam!"

Daniel: "Oh geez..."

Teal'c: "I am sorry Daniel Jackson."

Teal'c: "Are you injured?"
Daniel: "Dumb question. But thank you."
Teal'c: "You are welcome."
Daniel: "Just don't ever do that again."

Jack: "You did it Sam. You won."