The King's Gambit — John McNichol

Fast-paced light-hearted science fiction with Catholic themes for ages 9-12. Edward's dad has been missing for two years when suddenly strange things begin to happen: A knight on horseback bursts through the stacks at the library and attacks Edward; strange infantry soldiers appear at Edward's school; and suddenly the FBI and Homeland Security get involved. Edward has to rely on his wits to find his father and find a way to bring him back.