While on holiday, Modo and fellow spy Octavia Milkweed find themselves in Ember's End. Created by the slightly mad scientific genius Dr. Ebenezer Ember, this is no ordinary wild-west town. It is surrounded by an energy field that prevents gunpowder from firing, and messages are sent via pneumatic tubes. There are also rumors that before Dr. Ember died, he built a weapon so powerful it could end all wars. With the local sheriff recently deceased, the two travelers are suddenly put in charge of Ember's End law enforcement.