Jonas returns to SGC with news on the Thanos crystal they were analyzing – they determine that naquadria was imported to Kalowna (now renamed "Langera") and the process that transformed naquadah into naquadria is ongoing, and threatens to destroy the planet. While the SGC deals with the representatives of the three nations and try to arrange relocation, Sam and Jonas figure out the transformation is a recent event by the naquadria bomb tests that killed Daniel (in "Meridian").
The team comes up with a way to stop the chain reaction by taking a nuclear bomb down to open a fault line and cut off the advance of the conversion process. Fortunately there's an underground drilling machine available that Jonas created with the help of his assistant and girlfriend Kianna Cyr. Sam notices similarities in the technology to Goa'uld systems and determines Kianna is a Goa'uld spy working for Ba'al. She offers her help to save the planet but the Kalownans turns down her offer. However, they need her to make it work so they eventually okay her participation with Teal'c and Sam riding shotgun . . while Ba'al prepares to approach the planet if he doesn't hear from her.
While SGC tells the Kalownans to take a hike to break their negotiation stalemate (based on Jack's suggestion), Kianna claims to have feelings for Jonas and when the drill machine is stuck, Kianna volunteers to enter a Tok'ra crystal tunnel and deliver the warhead, relying on her symbiote to protect her. When they lose power, Kianna advises them to leave without her. Jonas tells her to get back and she manages to return just in time and the mission is a success. The symbiote dies healing the Keana host, who returns with Jonas to Kalowna.