Stargate Atlantis/Recap/S03 E18 Submersion

"You are all about to die."

- Wraith Queen

Sheppard takes a science team to check out an Ancient underwater drilling platform to serve as a power source for Atlantis. A science team that includes Weir for some reason, but oh well. McKay and Zelenka get everything up and running, but Teyla senses a Wraith presence. The life signs detector reads negative, but Teyla tries to make contact just to be sure. After assuming the Lotus Position and rolling her eyes back in her head, she comes back and reveals...that it was a false alarm. No Wraith anywhere, no siree.

They continue checking out the base, but Teyla seems unusually quiet. At the first opportunity, she takes down Ronon and starts shutting off essential systems and throwing up forcefields everywhere. Sheppard manages to catch up with her, but she passes out as the Wraith Queen relinquishes control of her body. Oh yeah, and there's a Wraith Queen, who just swam into the base to continue messing with things (and eat the science team).

It turns out that there's a ten thousand year old downed Wraith cruiser not far away on the Ocean floor. The Queen came on over in response to Teyla's mental searching, and wants Sheppard to fly her off the planet in the puddlejumper. Unfortunately, said Jumper was rendered inaccessible when a missed shot from Ronon accidentally let the sea in - so the Queen rigs her cruiser to explode and take them all with her. Especially since the crust is very thin just here (hence drilling platform), so an explosion would trigger things to take out much of the planet.

Sheppard and McKay take a walk across the ocean floor to the Cruiser, then radio back that they've gotten it up and running again, and Sheppard intends to pilot it out of here. The Queen returns to the Cruiser and disables the self destruct, intent on forcing Sheppard to fly her out. So McKay shoots her, and the crisis is averted.

Tropes:

 * Groin Attack: Teyla to Ronon
 * Not Herself: Teyla. For what it's worth, Teyla has gotten taken over by a Wraith in the 18th episode of every season so far; they should really be used to it by now.
 * Self-Destruct Mechanism
 * Underwater Base: in this case, an underwater drilling platform.