Later, Martouf arrives at Stargate Command, escorting a group of robed men carrying Graham's body. Anise follows soon after.

As it turns out, Per'sus suffered only minor injuries, and the Tok'ra are not accusing Stargate Command of any complicity in the attack. Anise believes the attack is the work of Goa’uld mind control technology that turns the victim into something she calls a "za'tarc."

O'Neill is obviously irritated to once again learn vital information after a disaster, but this time though he finds himself on the same side as Anise, which irritates him further.

It may only take moments of contact to turn someone into a za'tarc. However, the Tok'ra Council wants more evidence before pursuing a course of action.

O'Neill insists that the summit should be called off, but Martouf disagrees, saying that the Tok'ra have not bowed to Goa'uld terrorism in 2,000 years and won't start now.

Hammond decides that the best course of action is to test everyone with Anise’s handy za'tarc detector while preparations for the summit continue. No one at SGC is particularly happy to rely on Tok'ra technology to identify these potentially dangerous traitors in their midst.

Later, in the medical lab, Anise examines Lieutenant Astor, one of the members of Graham’s team, while Martouf and the members of SG-1 watch.

Martouf explains that the za'tarc detector uses a modified Tok’ra memory-recall device to compare the subject's unconscious memories to his or her conscious account of events. In other words, it is a mnemonic lie detector, capable of determining whether memories have been tampered with, but not the specific instructions the Goa'uld may have imbedded behind the conscious mind.

Anise asks Astor about the recent mission. She recalls the battle, providing a panoramic sense of the cosmic war effort going on against the Goa'uld.

As it turns out, Astor is indeed a za'tarc. Anise claims to have a way to remove the program but it is experimental and dangerous. They give Astor the choice and she decides to go through with it, since the unconscious programming, once triggered, will mean her death.

Unfortunately, the procedure fails. Astor suffers great pain, then escapes her restraints and kills herself.

Anise speculates that the Goa’uld have built in a failsafe that triggers the self-destruct command if the programming is tampered with. She apologizes for not knowing this before, but Hammond says the Goa'uld are the ones who are ultimately responsible.

Hammond informs the president, and Carter and O’Neill are put into quarantine. Both the Tok'ra and Stargate Command decide that the summit is still on, but all known or suspected za'tarc have to be kept under guard to minimize risk.

Anise visits O'Neill in his cell to apologize, since she feels responsible for the armband incident as well. She then leans over and kisses him, which definitely freaks him out.

In turn, she seems unnerved by his reluctance and wants to know if he finds her attractive or if he has a relationship with someone else. He tells her that is not the point. She leaves.

While Martouf and Jackson fine-tune the treaty's wording to make it acceptable to both sides, Anise, always helpful, comes in to announce that she has come up with a new and disturbing theory -- maybe za'tarc prevented from achieving their objectives will self-destruct on their own.

Martouf goes to Carter to break this bad news, while Jackson explains to O'Neill. Basically, both have the choice of being sedated indefinitely or undergoing Anise's experimental procedure. Carter refuses the process, but O'Neill decides to go through with it -- even if it doesn't succeed, they might learn something new to save Carter.

Back in the gate chamber the gate opens and Per'sus walks through with his entourage. Jackson is looking dapper in his best suit, but he is obviously worried about Jack.

Carter is sedated while O’Neill straps in for deprogramming.

Hammond goes to meet the president and escort him down to the summit.

As Carter is going under, she relives her memories of the armband mission, groggily telling Dr. Fraiser that she and Jack lied when Anise was first testing them.

Fraiser stops O'Neill from undergoing the deprogramming procedure, then send Carter in for a moment alone with Jack. She says they were lying about their feelings for each other, that they left out the reason he stayed behind to save her when they were separated by force screens.

It was this lie born out of embarrassment that caused the machine to identify a discrepancy between their memories and their conscious accounts.

Carter has O'Neill retested. He flashes back to scenes from Apophis’s ship and Sam caught behind the force shield. Finally, he admits that he did not leave because he would rather die than lose Carter, for whom he cares more than he is supposed to.

Anise determines that neither is actually a za'tarc, and all agree that nothing they learned today will leave the room.

Back in the gate chamber, everyone waits on the presidents arrival. Jackson receives a message from Carter and O'Neill and asks Martouf to walk outside for a second.

As the president walks in, Martouf pulls out a finger blaster and starts to fire. Everyone survives except for the hapless assassin, who Carter kills before he can kill himself. In a heartwrenching moment, the episode ends with her holding his body in her arms.