Daniel Jackson and SG-1 are stunned when Vala Mal Doran (Claudia Black) makes contact with them from the distant Ori home galaxy, where she has been living safe and sound these past several months. Vala was pulled into an intergalactic wormhole in the act of thwarting the Ori's attempt to create a planet-sized Stargate for their invasion ("Beachhead").
Vala makes contact using an Ancient long-range communication device, which links her to Daniel. She remains in the village where she now lives, but can speak to the team through Daniel. In this way she tells them what has happened to her, and informs them about the Ori's impending invasion ... and her own mysterious pregnancy.
After being pulled through the wormhole Vala ended up on a planet populated by followers of the Ori. She was found unconscious by Tomin, a lame man with a kind and gentle soul, who cared for her. The two were eventually married, and she soon found herself pregnant -- though, inexplicably, not by sexual union.
But Vala has been forced to keep her feelings about the Ori to herself, as Tomin and the rest of the village are devout followers who are helping to build the Ori's invasion fleet. Denya is a local bar maiden and harlot, and the two have struck up a friendship. But the local barkeep and her employer, Seevis, is a powerful man who metes out punishment due to those who stray from the path of the Ori.
Elsewhere, General Landry makes a discovery about one of the S.G.C.'s closest allies: the Russians. He confronts Colonel Chekov (Garry Chalk) about his plans to manipulate other nations to his own advantage.
Through her connection with Daniel, Vala tells General Landry and SG-1 that the Ori's followers are building ships and armies by the tens of thousands. It is just as they feared: since Daniel first met them, they have been amassing a great force for a crusade against Earth and our galaxy. And the latest recruit to the holy war is Vala's husband, Tomin.
Tomin is overjoyed when a Prior heals his leg, and believes that the Ori have smiled upon him because of his compassion toward Vala. As a cripple he has always been a second-class citizen, and is thrilled that he has been not only healed but also conscripted as a warrior of the Ori. Vala genuinely cares for the man, but is gravely dismayed by his eagerness to travel millions of lightyears to slaughter innocent millions in the name of the Ori.
But in speaking with Denya, Vala has eventually learned that even among these people, seemingly the most devout followers of the Ori, there is an anti-Ori resistance movement. Denya is a member. And Seevis himself, who tortures Vala by depriving her of food and water for days to try and learn her true feelings about the Ori, is the movement's leader. His religious zeal is just a cover.
Now, the anti-Ori movement is undertaking an ambitious plan to destroy the Ori's new fleet. In an upcoming demostration that will see the Priors activate ten ships in a show of strength, they hope to cause a chain reaction that will destroy them all.
It was at this point, Vala says, that she revealed to them who she is and where she came from. Seevis then shared a discovery with her: the Ancient communications device she is now using.
Will the underground plot against the Ori succeed ... or is an unstoppable fleet on its way to the Milky Way Galaxy even now? Can Vala find a way to return home? What of her child? And when the Priors turn the increasingly fanatical Tomin against his wife, will she survive at all?
