From back cover of Jove/HBJ paperback February 1979:

terror from space

The pirates of Boskone raided at will, menacing the whole structure of interstellar civilization. Masterminded by a super-scientist, their fleets outgunned even the mighty space cruisers of the Galactic Patrol.

When lensman Kim Kinnison of the Patrol found the secret Boskonian base, it was impregnable to outside attack. But a single infiltrator might penetrate its defenses -- if he wanted to take on million-to-one odds!

Kinnison took them -- with the future of the civilized Universe riding on his shoulders!