It's a thirties adventure story with intrepid explorers tracking down a crazy legend in the Siberian arctic. In the arctic, they find a huge unexplored mountain range. They find an entrance to volcanic caves inhabited by degenerate cannibal cave men!!! They are almost literally boiled in a cauldron like bugs bunny when they are saved by warriors from a lost kingdom on the other side of the mountains.
There they find an Art Deco kingdom ruled by an immortal woman with magic powers. There's some jealousy and love triangle and mistaken identity and blah blah blah.
This movie has some amazing matte paintings and costumes (the immortal queen was the inspiration for the evil queen in Disneys Snow White). And did I mention there's a saber tooth tiger and its last victim frozen in a glacier? From only 500 years ago!
The film also gets bonus points for explaining why the lost kingdom speaks English. Plus they have their own fictional language.
The ending is amazing. The entire sacrificial procession and dancing! The rituals and masks! The giant statues of gods sitting around the chamber! My eyes boggled! The design and choreography and costumes and set design just all come together to be perfect pulp adventure film. The special effects of the Flame of Life at the very end were amazing, even by today's standards. They were beautiful and mysterious and very modern looking.
The whole movie is like a pulp-adventure rpg campaign come to life! This movie should be required viewing for anyone wanting to run a pulp adventure RPG.