Kimball Kinnison is a Lensman and an officer of the Galactic Patrol, a kind of interstellar police force with almost unlimited powers. The Lens gives its wearer a variety of mental capabilities, including those needed to enforce the law on alien planets, and to bridge the communication gap between different life-forms. It can provide mind-reading and telepathic abilities. Kinnison is sent on a mission to fight the pirates of Boskone, an evil empire of enormous power and unimagined technological capabilities.