Tough Guy Trask murdered an officer of Space Patrol, causing him to serve a life-sentence in a labor camp on one of the moons orbiting Jupiter. He has a discussion with a Martian named Gror. Gror tells Rocky of his plans to escape on the next spaceship to arrive and shows Tough Guy Trask his "Martian gas gun". Trask is working on a bridge over a valley. He intentionally bumps Gror off onto a ledge below, killing him. Rocky rushes to Gror's lifeless body and retrieves the gun.