Galactic Patrol

Third volume in the classic series, and the first to feature superman Kimball Kinnison.
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.
Lensman Kimball Kinnision of the Patrol found the secret Boskonian base. It was impenetrable to outside attack, but a single infiltrator MIGHT penetrate its defenses, if he wanted to take on million-to-one odds.
Kinnison took them, under the impression that he was combatting normal beings. When his lens touched the mind of an Eddorian, a monster from beyond time and space, he realized that the future of a galaxy depended upon his ability to get out alive.