Dr. Rodney McKay, Maj. John Sheppard, Dr. Brendan Gall and Dr. Abrams are in Puddle Jumper One. In addition to McKay getting some much-needed flying lessons, the team's mission is to find the Lagrangian point satellite discovered by Dr. Gall. What they find is an enormous Ancient weapons satellite as big as a Goa'uld mothership. Unfortunately, it's completely inoperable. Abrams then picks up a signal from the planet below. It is a Wraith distress call.
Sheppard radios Dr. Weir at Atlantis that there is a crashed Wraith ship on the planet that warrants investigation. It's supposed that the Ancient weapons satellite shot the ship down 10,000 years ago during the final battle for Atlantis.
On the planet, Sheppard and his team move toward the Wraith ship. They encounter a glowing "firefly" - or, as Sheppard calls it, a "space bug" - that is giving off intensely strong life-sign readings. It seems attracted to the PowerBar snacks the men are carrying.
Outside the ship are Wraith skeletons. Inside, the team finds another dead Wraith, which McKay says is either remarkably preserved or only recently deceased. The corpse has Wraith feeding marks on its chest, implying Wraith cannibalism. The team then finds a cocoon chamber with thousands of pods that once held live humans for the Wraith to feed on. This was a supply ship.
Sheppard and McKay move toward the bridge, leaving Gall and Abrams behind. McKay and Sheppard wonder how long a Wraith could have survived on all those bodies back there; they surmise that is possible that, if the humans were kept alive by some yet-unknown means, a Wraith could have fed off them for thousands of years, further sustaining itself through hibernation and, as a last resort, feeding on other Wraith. Sheppard orders Gall and Abrams to get back to the jumper, but they are attacked by a lone Wraith. Sheppard and McKay double back to find Abrams, dead and aged.
Back at Atlantis, Weir, acting on intuition, sends a rescue team, including Lt. Aiden Ford and Teyla, to Sheppard's coordinates. Inside the Wraith ship, Sheppard and McKay find Gall cocooned, aged nearly 40 years but still alive. He tells them that the Wraith is heading towards the jumper. Sheppard takes weapons off the dead Wraith they found earlier and tries to get to the jumper before the Wraith does, leaving McKay to tend to Gall.
But the Wraith has reached the ship first and found a 9mm pistol. He's also trying to hotwire the jumper; because he lacks the Ancient gene, the ship won't obey him unless he bypasses its security. Sheppard tricks him out of the jumper by taunting him over the radio, telling him that he is waiting for him at the Wraith ship. When the Wraith comes out, Sheppard fires a barrage at him from his P-90. But the Wraith heals itself and fires at Sheppard, hitting and disabling his P-90. Sheppard hurls one of the Wraith grenades he found in the enemy ship, resulting in the Wraith being blown back; to his dismay, it survives. This is no ordinary Wraith.
Gall, rather than live as an old man - and to give McKay the freedom to help Sheppard - kills himself with his sidearm.
The Wraith corners Sheppard and attempts to feed. Sheppard jams his knife into the Wraith's hand. The fiend removes it and is about to use it on Sheppard when it is shot in the back - by McKay! The Wraith charges McKay, who empties his 9mm into the creature, to no effect.
Sheppard takes his last PowerBar out of its wrapper and throws it near the Wraith. A swarm of "space bugs" engulfs the Wraith, who tries to swat them away. Ford and the rescue team reach orbit of the planet and radio Sheppard, who orders them to fire on the energy signature created by the mass of space bugs. The Wraith is blown to smithereens.
As Sheppard and McKay walk back to the jumper, the major promises McKay that he can drive home.