Exiled to Earth and now working for UNIT as their scientific advisor, the Doctor (Jon Pertwee) is summoned to an underground research center at Wenley Moor to investigate a series of inexplicable power losses. Initially suspecting sabotage, he soon discovers that the nearby cave system conceals a colony of an ancient race called the Silurians. Awaking from a hibernation which has lasted millions of years, they are now planning to reclaim the Earth from humankind.
Commentary by actors Caroline John (Liz), Nicholas Courtney (The Brigadier), Peter Miles (Lawrence) and Geoffrey Palmer (Masters), director Timothy Combe, producer Barry Letts, and script editor Terrance Dicks
What Lies Beneath Cast and crew explore how the socio-political climate of the late sixties shaped this story
Going Underground Making Of
Now and Then Location featurette
Musical Scales Retrospective on an era of musical experimentation in Doctor Who
Color Silurian Overlay Featurette showing how the story was restored to full color for DVD release