Skylark of Valeron (Skylark Series #3) (Pyramid SF, T2237)

SUMMARY: The incredible staship Skylark Three has fought the Fenachone Supermen to a standstill, and Richard Seaton has gone back to his first love - exploration. Roaming the galaxy, he discovers a world of disembodied intelligences; a world of four dimensions where time was insanely distorted and matter obeyed no terrestrial laws, where 3-dimensional intellects were barely sufficient to thwart invisible mentalities! Meanwhile, the villainous DuQuesne is allying himself with the remnants of the Fenachrone, and planning his next attack . . . Part of the all time best Science Fiction adventure series