TV-PG
S7 • E19 May 8, 1970 25m8.1
Project Inferno is designed to drill down to the center of the Earth, where it will release a wonderful new energy source called Stahlman's Gas named after the project's director. But the Doctor realizes that unleashing Stahlman's Gas will have horrible consequences from the planet, fears confirmed when a power surge in the TARDIS console sends him to a hostile parallel universe where the project is nearing completion.
