Daybreak 2250 by Andre Norton / Beyond Earth's Gates by Lewis Padgett and C.L. Moore

Paperback. Condition: Good. 1954. Ace Double Novel.

Beyond Earth's Gates:
Under Eddie Burton's management the ambitious starlet Lorna Maxwell seemed headed for the top of Broadway's glamorous world of make-believe. And then she vanished - through a wall where there was no door. Eddie found himself plunging after her into a city beyond reality.

In that weird twin city to New York, Eddie became a hunted fugitive while his girl friend turned up as an ever-present face and all-pervading voice that awed and mystified the inhabitants. And Eddie learned that between him and return to his natural home stood her new manager, a mysterious figure who ruled by a tyrannical combination of super-scientific miracle and brute force.

Daybreak - 2250 A.D.
Two centuries after an atomic war on earth, a silver-haired mutant sets out on a dangerous search for a lost city of the ruined civilization.