More pulp peril from Project Gutenberg.
The Einstein See-Saw by Miles John Breuer
"In their pursuit of an unscrupulous scientist, Phil and Ione are swung into hyperspace—marooned in a realm of strange sights and shapes."
The World Beyond by Ray Cummings
"Out of nowhere came these grim, cold, black-clad men, to kidnap three Earth people and carry them to a weird and terrible world where a man could be a giant at will."
Breuer's story was written is the shadow of prohibition and features a scientific super villain.
Cummings' story is a variation on the basic plot of his best work, The Girl in the Golden Atom.