Earth's Last Citadel

Well as I said most of SF from that period has historical value but the SF used or thought are completely surpassed and most people cannot understand those books or ideas. Well this book is about four people. Two allies (one american spy and one scottish scientist) and two Axis (one renegade american and one german girl) who stumble upon an alien craft in the Sahara and they are catapulted into the far future on a dying earth where aliens control a bred some of our own human descendents.
As I said this book is in the beginning of the SF era and at my modern measure I thought this book was dull and pretty small. There is no depth to the characters and the story relies on imagery like as they arrived and the moribund earth is populated by giant worms and fylging creatures and the views are shrouded in continuous mists. This part of the book drawns there and makes us feel the desolation and melancholy of our beautiful earth. The aliens are portrayed as devilish beings that are sucking the life of our earth and they resemble more akin to Lovecraft's aliens than anything else. I wouldn't advice to read this book as a CL Moore story or Henry's Kuttner. No Boundaries is far better... Then come back to this one.
The book is quite small and at the end starts being a little strange with the plot being quite strange and confusing...