Explorer Paul Raymond has set his mind to proving to his colleagues at the club that there are mysteries to be found in the Sargasso Sea. He travels there, encounters a race of fish men and manages to bring back one of the creatures. But Larpo murders the president of the explorers’ club and swims off. Raymond is apprehended for murder and put away in a mental institution.; Scientist Martin develops a test machine for rocket flight capable of accelerating with over 10 Gs of gravity. During a test run pilot Major Blake is overexposed and transformed into a brutish creature from a neighboring dimension. Martin learns of the aliens’ plan to conquer earth and destroys his machine by sacrificing himself.; Two years ago convicted killer Caesar Renard survived a volcanic eruption which buried the prison he lived in. Now he surfaces from his underground hideout to stalk and murder the commissioner who put him into jail. They wrestle atop the volcanic pit and fall to their deaths.; A hooded figure calling himself Vengeance calls upon down-and-out lawyer Arthur Drake. He pulls Drake out of the gutter and makes him a member of his criminal gang. Vengeance poses as an all-powerful demon, but has only drugged his underlings to believe so. Drake is able to resist and puts an end to the crime spree.