There’s something about Unknown World (1961) that ticks the right boxes for me. It has since I first stumbled upon it while channel surfing years ago. I get why it has the reputation for being dull: it’s an hollow earth story with no monsters or lost civilzations (or really antagonists of any kind), a lot of it takes place in the rather banal interior of the “cyclotram,” and Terry Morse’s direction lies at the intersection of workmanlike and pedestrian.

