Craig Veroni

Dr. Rodney McKay (David Hewlett) undergoes experimental gene therapy altering his DNA to match the Ancient genetic coding. The experiment opens up countless scientific possibilities as well as an unexpected problem. Meanwhile during a game of hide and seek one of the Athosian children inadvertently opens a containment unit that lets loose a seemingly harmless black ethereal cloud. But when Atlantis goes through a series of technical malfunctions they realize that the shadowy creature is actually feeding off of the power supply!

Fleeing from a surprise encounter with the Wraith Major Sheppard (Joe Flanigan) falls victim to an alien symbiote which is feeding off his life force and slowly paralyzing him. While speeding back to Atlantis for medical aid the team gets trapped halfway through the Stargate when the puddle jumper damaged in the altercation with the Wraith suffers a mechanical failure. With only thirty-eight minutes before the Stargate shuts down Lieutenant Ford (Rainbow Sun Francks) and Dr. McKay (David Hewlett) struggle to manually fix the problem. As the clock ticks away the Atlantis team must come together or perish in the harsh vacuum of space.

With the Wraith armada closing in on Atlantis Dr. McKay (David Hewlett) and a small team attempt to repair an ancient weapons satellite in the hopes of leveling the odds in the coming battle. Meanwhile tension builds between Teyla and some of the other members of the Atlantis team over her connection to the Wraith. Major Sheppard (Joe Flanigan) steps in to defend her but even he begins to harbour doubts when a team member is left unconscious after an attack by an unknown assailant.

Engaged in combat the Atlantis team's puddle jumper is hit with an energy wave that leaves them unharmed but destroys their Wraith attackers. Hoping to find the source of the wave the team lands on the planet below. There they find a civilization enjoying the utmost health and happiness untouched by the Wraith. Their leader Chaya refuses to allow anyone other than her own people the sanctuary and safety from the Wraith that would be found by settling on their planet. Unwilling to give up so easily Major Sheppard (Joe Flanigan) asks Chaya to reconsider. After thinking it over Chaya surprises everyone by requesting to accompany them back to Atlantis to discuss the matter further leading the team to suspect they may be caught in a trap.

While assessing the structural damage to the city caused by a massive storm two of Dr. McKay's (David Hewlett) team of scientists experience horrifying visions. Minutes later they drop dead. Retracing the steps of the dead scientists McKay and his team find an Ancient lab its contents in disarray. Afraid of a viral outbreak Dr. Weir (Torri Higginson) places the city under a self-regulated quarantine. Even with the city under lockdown under the threat of a possible viral outbreak more and more people begin suffering from the same terrifying visions. If McKay cannot find a cure the entire city will be doomed.