What's the name of the book where a race of rat like aliens invade Earth and enslave humans using mind control?
Maybe this one?
CHANDLER, A. BERTRAM
Contraband from Otherspace (Ace, 1967, bound with Reality Forbidden by Philip E. High. (Ace, 1979, bound with Into the Alternate Universe. Magazine title was The Edge of Night.)
Grimes encounters a derelict ship that has drifted into our universe from a parallel one where ratlike aliens have enslaved the human race. Even worse, the aliens are aware of our continuum and are making plans to invade.