It features the return of Androvax, previously seen in the episode Prisoner of the Judoon, and of the android servants of the Alliance of Shades, last seen in the Doctor Who special Dreamland.
In 1972, ufologist Ocean Waters had her mind wiped by the robotic Men in Black, who gave her one of two activation discs to a hyperdimensional vault on Earth containing the last members of the Veil race, besides Androvax, in cryogenic sleep.
Wounded by a venomous viper and chased by the Men in Black that guard the vault, he asks Sarah Jane for help rescuing his race.
Sarah Jane refuses to help him because when the Veil are reawakened and their spaceship takes off, the dimensional disturbance will destroy Earth.
At Sarah Jane's urging, the last of the Men in Black, Mister Dread, gives up his energy to safely teleport the spaceship into space, to allow Androvax and the Veil to leave Earth without harming the planet.