The narrative follows Larry Barlow, a young machinist and aspiring inventor who lives with his sister and devises a patent extension ladder intended for firefighting. Motivated to join a major city fire department, he travels to New York, earns a place after demonstrating bravery at a blaze, and undergoes formal training. Along the way he rescues and befriends a young woman, becomes embroiled in a mystery about her inheritance, confronts rivals and criminal plots, participates in major fires including an oil-dock disaster and tenement rescues, and uses quick thinking to capture wrongdoers before a conclusive return.