On a winter's day in a British town, twelve-year-old Alex receives a package in the mail: an old tin robot from his grandfather. "This one is special," says the enclosed note, and when strange events start occurring around him, Alex suspects this small toy is more than special; it might be deadly.

Right as things get out of hand, Alex's grandfather arrives, pulling him away from an attack--and his otherwise humdrum world of friends, bullies, and homework--and into the macabre magic of an ancient family feud. Together, the duo flees across snowy Europe, unravelling the riddle of the little robot while trying to outwit relentless assassins of the human and mechanical kind.