The crew of Puddle Jumper One has narrowly escaped the Wraith while on a recon mission to that hostile race's homeworld. The team had discovered that the Wraith hive was not simply within a tree-covered mountain; it was that mountain — and it has now evidently flown off into space. However, the Wraith left behind warriors who attacked them, as well as a scorpion-like parasite that has attached itself to the throat of Maj. John Sheppard — putting him in great pain as it tries to suck the life out of him. Also aboard the spacecraft are Lt. Aiden Ford, Sgt. Markham, Sgt. Stackhouse, Dr. Rodney McKay and Teyla.

As they approach the stargate orbiting the Ancients' planet, the Puddle Jumper's damaged engine pod fails to retract, and the ship gets jammed in the stargate aperture. Horrifyingly, the front half of the ship, containing Markham and Stackhouse, becomes stuck in the 'gate's event horizon, while the other half remains in space. McKay points out that, according to wormhole physics, they have 38 minutes before the 'gate automatically shuts down. The dematerialized fore of the vessel, along with those inside, will cease to exist, and the other half will be severed and sent floating in space with everyone inside exposed to the vacuum of space. The clock is ticking.