In an alternate 1875 America electricity is forbidden, Native Americans and Yankees are united, and eldritch evil lurks in the shadows. Young Archie Dent knows there really are monsters in the world. His parents are members of the Septemberist Society, whose job it is to protect humanity from hideous giants called the Mangleborn. Trapped in underground prisons for a thousand years, the giant monsters have been all but forgotten - but now they are...

Wielding the Dragon Lantern, the maniacal Philomena Moffet unleashes a monster army on the American continent, forcing Archie to put aside his reservations about his league membership and rally his forces to stop the threat.