Grey Lensman - Lensman Series Book 4
Description from the back of the book
Somewhere among the galaxies was the stronghold of Boskone - a network of brilliant space-criminals whose hunger for conquest threatened the continued existence of all known civilisation.
But where was this stronghold? Boskonian bases were scattered across the universe - shielded by gigantic thought-screens that defied penetration. The best minds in the Galactic Patrol had tried. And failed. Now it was up to Lensman Kim Kinnison, using his fantastic powers to infiltrate the Boskonian strongholds, find the location of the enemy's Grand Base - and smash it forever.
But Kinnison didn't know then that the power of Boskone reached further than anyone had dreamed - into the Galactic Patrol itself...
Condition - Very Good, Creases on the spine and yellowing pages.