When an alternate 1875 steam-driven America rediscovers electricity, the lifeblood of the Mangleborn monsters, and the secret society to protect humanity from the Mangleborn is compromised, twelve-year-old Archie must assemble a team of seven young heroes to save the world.

Archie Dent and his friends Hachi and Fergus, the first three members of a new League of Seven, a group of heroes who come together to fight the Mangleborn whenever the monsters arise to destroy humanity, undertake separate missions and in the course of their adventures meet potential candidates to join their League, while learning deep-rooted secrets that could destroy the League forever.

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.

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.