SG-1 discovers that their recent trip through the Stargate may have inadvertently doomed an entire civilization.

The Tollan offer Earth advanced weapons technology, prompting a secret investigation on Tollana -- one that leads to a startling discovery.

SG-1 trains a team of raw cadets, and Colonel O'Neill is forced to take them into a real-life battle situation when he learns of a possible alien incursion at the SGC.

SG-1 must turn to a pair of convicted criminals to save a world from annihilation by the Goa'uld.

The team returns to Earth with a piece of technology that allows them to see alien creatures everywhere, and must attempt to contain the problem when it spreads beyond the base.

A businessman threatens to expose the secrets of alien life to the world, forcing Stargate Command to bring him into the loop.