A young inventor famed for mechanical wonders learns that a friend in Mexico has disappeared and that a bandit leader controls a rich mining claim. He outfits his New Steam Man and gathers loyal attendants for a long expedition into hostile country to investigate, confront the outlaw gang, and attempt a rescue. The episodic narrative mixes descriptions of inventive machinery and technical preparation with chase sequences, skirmishes, mining-site danger, and daring escapes, moving through successive chapters that alternate engineering detail, travel, and action-driven encounters.