- Okay. Perhaps you've noticed, but every time we step through the Stargate, bad guys try to kill us. And I'm getting a little tired of it. How about you?— Major Sheppard
The Atlantis Mission has a problem: the Wraith seem to know their every move, and have ambushed them on 5 out of their 9 off-world missions - even the ones to planets that are uninhabited. McKay proves the severity of the situation by getting shot in the face in the first five minutes of the episode. Obviously, there is a mole in the city. Weir suspends all gate travel until she's had a chance to
interrogate interview each of the Athosians.
Tensions rise between Sheppard and Sgt. Bates, who is conducting the investigation, between Halling and Teyla, who is seen as a collaborator against her own people, and between the Earthlings and the Athosians generally. So when McKay and Zelenka figure out how to open an upper hatch above the Jumper bays, Sheppard and Ford head out for a stroll around the planet. They discover a large (about four times the size of the United States) and apparently habitable landmass only 25 minutes away by Puddle Jumper.
Bates wants to immediately deport all of the Athosians to the continent, thereby solving the security problem. Sheppard is horrified by the suggestion, but they are saved from a sticky moral debate by Halling independently volunteering to take the rest of the Athosians (who had been grumbling about leaving anyway) and explore the continent. Teyla stays behind, as a member of Sheppard's team and the one Athosian who has been above suspicion this whole time. With the Athosians gone, they resume normal gate travel.
On the first fascinating planet they visit, however, Teyla and Ford go off on their own to try to make contact with the local people. Teyla insists that she will do better completely alone, but the moment she is out of Ford's sight the Wraith attack the rest of the team. Sheppard goes down and they retreat through the gate. Teyla checks in, dragging an unconscious Ford, sometime later. Weir reluctantly lets them through, but when Ford reveals that he was hit from behind, and not by a Wraith weapon, Bates orders McKay to look through Teyla's stuff for hidden transmitters.
To his surprise, he actually finds one: the locket she always wears turns out to be a Wraith tracking device. Rather than confirming her as The Mole, though, this discovery has the opposite effect. The device is Ancient technology, which was dormant until Sheppard touched and activated it in the first episode. Teyla (and the Athosians) are exonerated, and Weir devises a way to use the locket as a trap for the Wraith. The trap works perfectly, and the base ends up with its very own captive Wraith prisoner, named Steve.
- Chekhov's Gun: Teyla's locket, introduced in the first episode.
- Cyanide Pill: crossed with Self-Destruct Mechanism in the case of the Wraith, who can push a button on their armor to explode rather than be captured.
- Red Herring Mole: Teyla, to some extent.
- Right for the Wrong Reasons: Bates was right that Teyla was giving away their location to the Wraith. He was wrong however that she was actually doing it on purpose. Her locket contained a tracking device she was unaware of.
- Stun Guns: It is revealed that Wraith weapons are intended to paralyze rather than kill, after McKay gets shot in the face with one. Which makes sense, since the Wraith would hardly design a weapon that would kill their prey before they got to feast on them.
- The team also uses Tasers to capture a Wraith alive, with limited success.
- Take a Third Option: Invoked, when the Athosians volunteer to leave Atlantis and explore and settle the newly-found continent. Halling actually says it: "We cannot leave. We cannot stay. This gives us a third choice."
- Tracking Device
- Witch Hunt: Outside the fact that they could have talked to Teyla about their suspicions first, the crew largely tries to be as diplomatic in their precautions as possible and Teyla later admits that they were reasonable concerns.