The story of Stargate SG-1 begins about a year after the events of the feature film, when the United States government learns that an ancient alien device called the Stargate can access a network of such devices on a multitude of planets. SG-1 is an elite Air Force special operations team, one of more than two dozen teams from Earth who explore the galaxy and defend against alien threats such as the Goa'uld, Replicators, and the Ori.

After young Clara receives a wooden nutcracker as a Christmas gift, she dreams about a fantastical battle between her Nutcracker Prince and the evil Mouse King. At stake is the Nutcracker's freedom - and Clara's future happiness.