One of the major expressions of American literary naturalism occurred in the cycle of Hollywood films made during the 1940s and 1950s commonly referred to as film noir. These films revisit and adapt nineteenth-century naturalist narratives via characters constrained by the forces of material environments, past experiences, instinctual urges, and mysterious fates. This article presents a close analysis of two of the most central and critically acclaimed films noirs, The Maltese Falcon (1941) and Double Indemnity (1944). These films blend naturalist narrative conventions with key cinematic devices: environmental constraints, emphasized through staging, high-contrast lighting, and low-angle cinematography; instinctual urges, emphasized through dialogue, costuming, blocking, and close-ups; and fate as a determining force, emphasized through dialogue, voiceover, and flashbacks. These conventions and devices find concrete expression in the thoughts and actions of the films' protagonists, who negotiate their desires for money and sex in the contexts of harsh environments, such as the criminal underworld, the private-detective business, an unsatisfying job, or a failed marriage. These negotiations often conclude with the characters succumbing to their greed and sinking into depravity or death; on rare occasions, however, these negotiations end with a hazy yet significant glimmer of hope. In each case, these movies attest not only to the power of film noir but also to the richness of cinematic naturalism.