Investigating the disappearance of an eminent scientist, the Doctor and his companions follow his trail to the London headquarters of International Electromatics, a global supplier of electronic equipment run by the formidable Tobias Vaughan. Teaming up with the newly formed United Nations Intelligence Taskforce (UNIT) under the command of Brigadier Lethbridge-Stewart, the Doctor soon suspects that Vaughan is working to his own sinister | Doctor Who: The Invasion | | DVD | Best Buy