Mark and Seth wrap up commentary for The Exploding Planet, the final part of the lost William Hartnell classic story Galaxy Four/
The Doctor, Steven, and Vicki race against time (and The Drahvins) to escape the doomed planet.
Bibliography
Galaxy 4 at TARDIS Data Core
Read the original BBC scripts
Galaxy 4 at Shannon Sullivan’s A Brief History of Time Travel.
The Internet Archive link to all the episodes