The 3rd Doctor (Jon Pertwee) is an observer and UNIT are providing security cover at an experimental drilling project designed to penetrate the Earth's crust and release a previously-untapped source of energy, named Stahlman's Gas after its discoverer.
Professor Stahlman dismisses the concerns of the project's Executive Director Sir Keith Gold and exceeds all safety margins in order to expedite the work. Soon however the drill head starts to leak an oily green liquid that transforms those who touch it into vicious primeval creatures with a craving for heat.
Special Features
- Can You Hear the Earth Scream? Cast and crew recall working on the story
- Doctor Forever! ? Lost in the Dark Dimension
- Visual Effects Promo Film Deleted Scene
- Pertwee Years Intro
- Doctor Who 1971 Annual (DVD-ROM)
- Radio Times Listings (DVD-ROM)
- Programme Subtitles.
- Production Information Subtitles
- Photo Gallery
- Digitally Remastered Picture and Sound Quality
- Commentary with actors Nicholas Courtney (Brigadier] and John Levene (Benton), producer Barry Letts and script editor Terrance Dicks
- Hadoke versus HAVOC Presenter Toby Hadoke reunites surviving members of the HAVOC stunt team and trains with them to perform a stunt himself
- The UNIT Family – Part One A feature looking at the Earthbound Doctor's ‘family’ during his exile to Earth and his new role as the UNIT scientific advisor