Lensman from Rigel

From the back cover of the Bantam first edition: An assassin's attack has nearly killed Second Stage Lensman Tregonsee, the brilliant telepathic intelligence chief of the Galactic Patrol. Their forces in disarray, the Rigellian super-brain and a rookie Tellurian Patrolman named D.D. Cloudd plan a desperate shell game to avert intergalactic devastation.