The Mars Cycle comprises Clark Ashton Smith's four sci-fi horror stories concerning the red planet:
The Vaults of Yoh-Vombis (Weird Tales, May 1932)
A group of explorers on Mars venture into the subterranean passages of a long-abandoned city ... with unfortunate consequences.
The Dweller in the Gulf (Wonder Stories, March 1933)
Three earthmen explore a mysterious cave system on Mars...
Vulthoom (Weird Tales, September 1935)
Two Earthmen on Mars find themselves trapped in the heart of a vast, underground city...
Seedling of Mars (Wonder Stories Quarterly, Fall 1931)
A great Martian being makes first contact with the human race...
