Synopsis: From the first page of the Ace Double: "Beware the planet-wreckers! The regime of the Zarles had turned Earth into Hell. Possessing strange unearthly perception, weapons of cosmic destruction, and motivated by an inhuman cruelty, these overlords from space had enslaved the Earth in a feudal terror. Then, one day, Jeff Gambrell, a human slave, defied his particular tyrant once too often and found himself facing the impossible challenge - how to escape. It had been done before, therefore he knew what what had always seemed impossible was not... Jeff's life and death struggle against the fiendish cunning of the Zarlesis is set against a startling background of unleashed interplanetary fury. Joseph E. Kelleam's new novel explores the frightening depths of man's inventive powers with brilliant detail and breath-taking power."