The mind of Simon Reilly, the 11-year-old son of alien superhero Doctor Vulcan is trapped in the body of the terrible Warmonster. His brilliant father lies in a coma. Unable to communicate, Simon finds himself attacked by an uneasy alliance of heroes and villains, joining together to save the earth. Simon's courageous mother, Maureen, goes to confront the mysterious Old Guard who have taken charge of Doctor Vulcan's body, claiming they are the only ones who can revive him. Meanwhile, Simon's older sister Sara, 16, has taken up the mantle of Doctor Vulcan and is hunting for Simon, unaware that a monster's mind inhabits his old body. At the same time, Nathan, Sara's twin, travels through hyperspace to search for Simon's best friend in a dinosaur-infested world.