The Doctor, Jamie, Polly and Ben find themselves in a remote space-colony inhabited by a cult-like group of 'gas miners' who take their orders from an unseen controller and are afraid to go out at night. The special effects seem ambitious (by Whovian standards) but, as all of the original episodes are lost, it is difficult to evaluate how well they were executed (the surviving still-images look interesting). I like Troughton's incarnation of the iconic Timelord and he seems to be having fun with the role in this somewhat silly tale. As usual, Jamie is an entertaining companion and Ben was central to the plot but Polly didn't add much to the story. All in all, the plot didn't make much sense and its hard to imagine a plausible back-story that could have set up the scenario in which the time-travellers find themselves. Even at only 4 parts, the story is a bit stretched and the big 'reveal' at the end of episode 3 isn't much of a surprise. The animation isn't great but serves its purpose. Essential viewing for completist-fans and well-worth the effort of making an animated recreation to replace the lost original, but overall a lesser entry in Troughton's Timelord tenure.