Plot: As the team embarks upon its tenth year, Vala, a former Goa'uld host turned freedom-fighter, joins SG-1 in their battle to defend the galaxy from the holy war of the Ori. Having discovered the existence of a weapon capable of defeating the Ori, the team is now in a race against time to find it before more systems fall to the influence of the Priors and the threat of the newly arrived Origin fleet