Ghost Dog is a quiet, solitary hitman who follows the ancient code of the samurai. He lives in a makeshift shack on a rooftop in a decaying urban landscape and carries out contract killings for the Italian-American mafia. Ghost Dog's only communication with his employers is through carrier pigeons. His loyalty lies with Louie, a low-ranking mobster who once saved his life and whom he now serves with absolute devotion, observing the warrior’s spiritual way of life as outlined in the Hagakure, an 18th-century samurai text.

Tension mounts when one of Ghost Dog's assignments, targeting a gangster, spirals out of control, and he inadvertently leaves a witness. The mafia, already plagued by internal strife and external threats, decides to eliminate all ties to him to clean up their mess. As Ghost Dog becomes the target, he continues to adhere to his strict moral code while evading attempts on his life, leading to a deep exploration of loyalty, honor, and the juxtaposition of traditional values in a modern world. As events unfold unpredictably, the principles of ancient samurai philosophy clash starkly with contemporary urban reality.