Deep underwater, the team scours the ocean floor looking for a mobile geothermal drilling station the ancients left dormant in hopes of unleashing near limitless power from beneath the planet's surface. The team finds the drilling rig and cautiously explores the station the Ancients chose to abandon. Using her gift Teyla (Rachel Luttrell) thinks she senses the presence of a Wraith but repeated life scans by McKay (David Hewlett) show nothing out of the ordinary. Weir (Torri Higginson), believing it's just the pressure affecting Teyla, has the team press on to explore the station. Without warning, Teyla suddenly attacks Ronon (Jason Momoa) and sets up a series of force fields to block the team from the jumper. But when Col. Sheppard (Joe Flanigan) corners her she has no memory of doing anything wrong. Using Teyla successfully as a puppet a Wraith Queen, now aboard the station, attacks two scientists to lure Sheppard to the jumper in hopes of using him to fly her to the surface. Unable to overcome the power of the Queen, Sheppard is helpless and saved only by Ronon mistakenly blasting the jumper windows sending a wall of ocean water onto Sheppard and the Queen. With the Wraith Queen now restrained and sedated Teyla uses her gift to learn that the Queen was part of the first wave of attacks on Atlantis. Her cruiser was shot down sending it plummeting to the ocean depths. Surviving only by feeding on her crew, she woke between centuries in the hope of a rescue that never came. Sensing Teyla's presence as they descended she awoke knowing the ship she sought had finally come. Wanting to either escape her watery prison or die the queen activates a self-destruct on her ship. If the team is unable to stop the resulting explosion over the thin layer of crust the drilling station sits on it would ignite a catastrophic chain reaction.