A close-minded new member of the International Oversight Advisory, Mr. Coolidge, orders all alien members of the Stargate Program to report to Earth for individual interviews. Fearing that Ronon - who lacks Teyla's diplomatic skills - might tear Coolidge's head off, Carter invites her old SG-1 teammate, Teal'c, to visit Atlantis and offer Ronon some warrior-to-warrior tips on how to cope with obnoxious Earth bureaucrats.
Ronon - confident that he can stay cool, and insulted that anyone would think otherwise - brushes Teal'c off. One epic sparring match later, nothing has changed. With Ronon still disdaining Teal'c's help, the two men depart for Earth via the intergalactic 'gate bridge.
Drs. Lee and Kavanagh greet the duo at the Midway station, halfway between the Pegasus and Milky Way galaxies, where all travelers must endure a 24-hour quarantine. Then the 'gate activates and a troop of Wraith invade the station.
As Wraith warriors fight Ronon and Teal'c, the Wraith commander and a Wraith scientist seize Midway's control room. The scientist dials Earth and sends a mysterious device through the 'gate to Stargate Command. When a horde of Wraith attackers follows the device through the 'gate to Earth, Ronon and Teal'c finally find themselves in total agreement. As one, they race through the stargate, pursuing the Wraith.
All of Stargate Command's personnel have been knocked unconscious by the Wraith device. Alone, Ronon and Teal'c battle the invaders, corridor by corridor. In one room, they find Coolidge, groggy but reviving. Refusing to trust Teal'c and Ronon to defeat the Wraith, the bureaucrat calls in a nuclear strike on the base to end the incursion, then makes a cowardly retreat to an escape hatch. If Stargate Command and its unconscious personnel are to be saved, it's up to the two alien warriors to do it.
Back in Atlantis, McKay and Carter discover that Midway is under attack. With a team of Marines, Sheppard and McKay 'gate to the station and battle the remaining Wraith. They retake the control room, where McKay and his fellow scientists struggle to regain access to the station's computers.
Wraith reinforcements arrive, pitting Sheppard and the Marines against an overwhelming onslaught. Soon, Sheppard is the only human left alive outside the control room. Then Kavanagh, working at McKay's side, triggers a Wraith booby-trap that activates the station's self-destruct mechanism.
With nothing left to lose, Sheppard orders McKay to vent the atmosphere from the entire station except the control room. The Wraith collapse, dying of asphyxiation - and Sheppard perishes along with them.
The battle is over, but with Sheppard presumed dead, the self-destruct counting down and an attack on Earth underway, McKay feels anything but victorious.