 In the episode, set in London, the alien Racnoss Empress (Sarah Parish) and the human resources head Lance (Don Gilet) attempt to use Lance's fiancée, the secretary Donna Noble (Catherine Tate), as a "key" to awaken the Racnoss children hibernating at the centre of the Earth by gradually and secretly poisoning Donna with an alien particle the Racnoss use as an energy source.The Tenth Doctor is shocked when Donna Noble, in a wedding dress, appears within the TARDIS while in flight.The Doctor returns Donna to her wedding.