The Skylark of Valeron: The Original Classical Edition (Unabridged‪)‬

The Skylark of Valeron is the third volume in the classic Skylark trilogy by E. E. Smith. 

DuQuesne has survived to become master of the Earth, ruling with an iron hand because the heroes, the Seatons and the Cranes, must run for their lives into the fourth dimension—from which dimension none have ever returned—from pure intellectual beings who can dematerialize them on a whim.

If you have ever wondered what it's like to exist in an extra dimensional world, E. E. Smith tells us here in graphic and exciting detail.

This was published in seven installments in Astounding Stories from 1934 to 1935.