Archie Dent is convinced that he and his friends Hachi and Fergus are 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. His belief is put to the test when they are forced to undertake separate missions. Archie and his faithful Tik-Tok servant, Mr. Rivets, pursue a shapeshifting girl who has stolen the Dragon Lantern, an ancient artifact with mysterious powers. And Hachi and Fergus travel to New Orleans to find Madame Blavatsky, the only person who knows the circumstances surrounding the death of Hachi’s father.

In the course of their adventures the three heroes meet potential candidates to join their League. At the same time, they learn deep-rooted secrets that could destroy the League forever.