"Steam Detectives" is set in Steam City, a metropolis powered entirely by steam technology, where towering smokestacks and intricate machinery dominate the skyline. The city is plagued by crime, with villains exploiting the advanced steam-powered gadgets for their nefarious purposes. The narrative centers on Narutaki, a young and brilliant detective who leads the Steam Detectives team. Alongside him are his loyal assistant Ling Ling, a nurse with exceptional combat skills, and Goriki, a powerful steam-powered robot who serves as their muscle. The trio works to maintain order in the city, solving crimes and thwarting the plans of dangerous adversaries.

The series introduces a variety of antagonists, each with unique steam-based weapons or abilities. Among them is Le Bled, a cunning and ruthless crime lord who frequently clashes with Narutaki. Another notable foe is the enigmatic Phantom Knight, a masked vigilante with a mysterious agenda. The detectives also face off against the Machinist, a genius inventor who creates destructive steam-powered machines to challenge them. These villains often operate within the shadows of Steam City, exploiting its technological advancements to further their schemes.

Narutaki’s investigations often delve into the darker corners of Steam City, uncovering corruption, conspiracies, and the misuse of steam technology. His deductive skills and resourcefulness are complemented by Ling Ling’s bravery and Goriki’s strength, making them a formidable team. The narrative balances episodic crime-solving with overarching storylines, gradually revealing more about the city’s history and the origins of its steam-powered innovations. Themes of justice, morality, and the ethical use of technology are woven into the plot, as the detectives confront the consequences of unchecked scientific progress.

The world-building in "Steam Detectives" is a key element, with Steam City depicted as a sprawling, industrialized urban landscape filled with intricate details. The city’s reliance on steam technology influences every aspect of life, from transportation to architecture, creating a distinct and immersive setting. The series blends elements of detective fiction, steampunk aesthetics, and action-adventure, offering a unique take on the genre. Through its engaging characters, inventive plotlines, and richly imagined world, "Steam Detectives" presents a compelling exploration of crime and justice in a technologically advanced society.