Celebrating two decades since "Doctor Who's" 1963 debut, this story finds a menace from the Time Lords' past so dangerous that it takes five of the Doctor's incarnations, a slew of companions, and some unwilling help from the Master to stop it. Peter Davison, Tom Baker, Jon Pertwee, Patrick Troughton, and Richard Hurndall star. 191 min. total on two discs. Standard; Soundtracks: English Dolby Digital 5.1, Dolby Digital mono; Subtitles: English (SDH); audio commentary; outtakes; photo gallery; more.