SG-1 boards an abandoned Goa'uld mothership that has mysteriously arrived in Earth's orbit, and must escape the doomed vessel when it crashes into the ocean.

A news reporter threatens to expose a top-secret military project, but when Carter and Jonas give her a tour of the X-303, they discover that she is a pawn in a much larger plot.

The team is called into battle unexpectedly when the Asgard homeworld is overrun by Replicators -- which have evolved into a startling new form.

General Hammond and the Pentagon reveal the existence of the Stargate to other world governments, and must defend the fact that the program is operated by the United States military.