It isn't easy being the head of security on an inter-planetary transport ship between Earth and Titan. Lieutenant Cal Hartland is not impressed when he's tasked to oversee the reintegration to Earth of mind readers who have been banished to a colony on Mars. Despite the fitting of cortical inhibitors, Cal is suspicious that the Minders are still dangerous, a fear that becomes personal when he has a startling emotional reaction to the leader of the small group, Commander Zero. Just as Cal is struggling to accept his feelings for the Martian, a mutilated body is discovered in the bowels of the ship. Why does Zero appear to know more about this terrible murder than any neutralised mind reader should? Trapped in the endless darkness of space and with the body count growing, can Cal trust anything about the enigmatic and beautiful Zero?