Earth is threatened with an extraterrestrial invasion and it's up to SG-1 to defend the planet. Using mysterious portals known as Stargates, this highly-skilled team scour the far reaches of the galaxy in search of the knowledge and alien technologies that will thwart a Goa'uld attack. Learn all about SG-1's O'Neill, Carter, Jackson, and Teal'c and join them on their top secret intergalactic missions, as they uncover the mysteries of new planets and encounter a whole host of new races—some friendly and some hostile.