Earth finds itself threatened by something even larger than the Goa'uld when the team learns that an asteroid is on a collision course with the planet.
Dr. Jackson's undercover mission to a Goa'uld summit is complicated by the arrival of a surprise guest. The rest of the team face a full-scale invasion of the Tok'ra homeworld.
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.
An alien ship approaches Earth, sending SG-1 to an old friend for some answers -- where they discover that Martin Lloyd has created a TV show about the Stargate program.
O'Neill and Lieutenant Tyler are ambushed by Goa'uld forces and trapped behind enemy lines -- while the rest of their team discover they don't know who Tyler is.
SG-1 finds themselves stranded in a crippled ship in a distant galaxy -- with Apophis threatening to destroy them. Teal'c is brainwashed and made loyal to Apophis once again.