Conner Raige's ancestors were on the front lines of victory against the Skrel, a long defeated enemy. Now he is one of the United Ranger Corps' most promising young cadets, despite his brash confidence and tendency to act on instinct. But when the Skrelreturn, a deadly ground war will test him to the limit. Only this time, the Skrel have brought a secret weapon: ferocious killing machines designed to eliminate humanity from Nova Prime... and the universe.