In the grim and dark alleys of Basin City, three men find themselves caught in the web of violence and corruption that blankets the urban sprawl, known to its residents as "Sin City". Hardened ex-convict Marv awakens to find the only woman who showed him kindness, Goldie, has been murdered while lying next to him. Consumed by the need to avenge her death, Marv embarks on a brutal quest to find her killer, his path marked by confrontations with law enforcement and a fearsome crime boss. This route through the city's underbelly reveals the depths of depravity that Marv must navigate to get justice for the woman he barely knew but for whom he would risk everything.

Meanwhile, private detective Dwight is drawn into the dangerous world of the Old Town, where the city's prostitutes maintain a delicate balance of power with the corrupt police. When an incident involving a corrupt cop threatens to destroy this balance, Dwight finds himself in a desperate struggle to protect the women of Old Town and to prevent an all-out war that could tear the city apart. Elsewhere, aging police officer Hartigan is locked in his own battle, striving to shield a young girl named Nancy from a sadistic serial killer with powerful connections. Each man is set on a collision course that will test their limits and force them to confront the heart of darkness within Sin City.