: The story is loosely based on the Greek legend of Jason and the Argonauts , specifically their quest for the Golden Fleece, with "Underworld" serving as a sci-fi retelling of the journey to Colchis. Critical Reception & Production

In this chapter of the four-part story, the Doctor and his companions explore a slave-labor mining society on a newly formed planet.

The code refers to Part Two of the 1978 Doctor Who serial titled " Underworld ". This episode is the 18th in the show's 15th season and features the Fourth Doctor, played by Tom Baker. Plot Overview

: This serial is notorious for its heavy use of Color Space Overlay (CSO) , a primitive green-screen technique, to create the cave settings. Reviewers from IMDb note that while the lasers and some CSO effects work, others look "simply awful".

Reports on the episode's quality are mixed, often highlighting the ambitious story vs. the limited production budget of the time: