The Doctor and Romana learn the second segment of the Key to Time is on the planet Calufrax. Yet they arrive on a planet called Zanak, which has been hollowed out and fitted with hyperspace engines, allowing its insane, half-robot Captain to materialise it around smaller planets and plunder their resources.
In this four part story, Tom Baker and his slightly superior companion "Romana" (Mary Tamm) are caught up in a time distortion that sees them arrive on a planet that's in the wrong place and controlled by the menacing "Captain" (Bruce Purchase). He rules with a rod of iron aided by his robotic falcon and his dedicated but put-upon assistant "Mr. Fibuli" (Andrew Robertson). As the plot thickens, we discover that this is but the shell of a planet that travels through space and time absorbing other worlds for their precious minerals - but not for money, for something altogether more nefarious. Can the "Doctor" discover the true purpose of this hunter-gathering before more planets are gobbled up - including our very own Earth? Perhaps not so well known, this series, but certainly one of my favourites as Purchase, (in)complete with false arm and glass eye yells for "Mr. Fibuli" time and time again as if he were Captain Bligh himself. We also have the "Mentiads" - a bunch of ostensibly peaceable mystics with telepathic powers and the always welcome contribution from K9 who manages to find himself involved in quite an enjoyable duel with his airborne counterpart. Baker brings a bit of mischief to his role here, too, and the visual effects do their jobs quite well for the time as the pair seek the second piece of the illusive "Key to Time".