Carter scans the area and declares it safe while Orner tells the team what little he can remember of the Vorlix and how the planet's elders have disappeared, leaving only portraits hanging in houses behind. Lyal chimes in, noting that all of the children are gone as well -- although in their case, no pictures remain.

Orner decides that he should take the SG-1 crew to Kira, the minister of health, science and restructuring and, as a ranking member of the Vias Transitional Government, the planet's de facto leader.

To the obvious annoyance of Lyal, he seems to have more than professional interest in Kira, whom we meet giving assistance to a woman suffering from a food allergy that she can't remember.

Once there, she impresses the planet's plight on O'Neill, painting a grim picture of the end of agriculture and industry as vital skills disappear.

Destroyer of worlds
When she asks where the SG-1 team came from, O'Neill tells her of the Stargate, which she takes in stride. Apparently, Vias has been visited before, as Kira has stumbled across papers that describe a traveler who claimed to use the Stargate.

The traveler's name was "Linea," a fact that causes no little distress among the Earth explorers. While Kira and Daniel talk about the Vorlix' possible origins in a DDT-like pesticide called "Dargol," the rest of the team compare notes about the sinister Linea.

As revealed in the second-season episode "Prisoners," the SG-1 team helped Linea escape from a prison on Hadante. After they equipped her with maps and access to the Stargate system, she showed her true colors by destroying an entire planet with an engineered plague, an act for which she earned the title, "destroyer of worlds."

Dr. Fraiser takes back a small group of natives, including Kira, Omer and Lyal, back to Earth to do some tests. In the infirmary the Viasians are shown some nice computer graphics of the brain revealing that deposits of Dargol in their brains are blocking their memories.

Love and forgetting
Daniel gives them a tour of the Stargate Command base. As so often happens, the tour ends with an awkward romantic moment between Kira and Daniel, but she breaks it off, explaining that the transitional government has banned intimate relationships out of fear of the consequences once memory is restored.

In her office, Carter tells O'Neill about Linea's diary, which she found on Vias. Linea kept careful accounts of how Dargol caused sterility -- which is why the people of Vias discontinued its use two decades previously -- but also slowed the aging process. Using enhanced versions of the drug, Linea tried to create a youth elixir.

Given this, it is likely that she eventually succeeded and introduced the elixir into the broad population, leaving it without children (due to the sterility effects) and no old people (who would have reverted to the prime of life). The amnesia is only a side effect.

Finally, Carter speculates, it is likely that Kira is Linea made youthful and ignorant by her own experiment.

Naturally, when they prove this last point through DNA testing and place Kira under house arrest, Daniel gets upset. Further complicating things, Carter and Dr. Fraiser find it impossible to remove the dargol blockage without help from Linea. As the "destroyer of worlds" is unavailable, they make do by creating an antidote, which they try out on Orner.

Orner goes into a seizure that seems fatal but then recovers, his memories now completely erased.

In a conversation with Daniel, Kira confronts him about their beliefs of her identity. Daniel shares the team's findings of the youth drug with her, and says that although the DNA test proves she is Linea, he believes she is a different person -- a person he will always care for.

Her morale apparently repaired, Kira helps Carter and Frasier adjust the antidote to the degree that she can see positive proof that it works. She then steals a sample of the antidote.

All's well that ends well
The second dose works on Omer, allowing him to remember his life and previous marriage, not to Kira, but to Lyal.

Daniel takes Kira back to her room and tells her he is going to tell her people about the cure, but he will come back for her. Ominously, she tells him "all debts are paid."

Affter a few moments, Daniel runs back to the room, remembering Kira's last words as Linea's original farewell message to the SG-1 team. He bursts in to find her about to commit suicide with poison gas.

O'Neill has figured out what is happening, and also bursts in, trying to kill Kira/Linea. However, Daniel talks her down by telling her that there is another way -- rather than die, she can forget.

The episode ends with Kira, under full grip of amnesia, going back to Vias in the company of Orner and Lyal.