The 1951 film adaptation of Tennessee Williams' 1947 A Streetcar Named Desire, directed by Elia Kazan, is comparable to the pattern of a person heading out to a bar looking to get lucky at the end of a night of drinking. This is a night with the hopes of getting lucky calls for advantageous lighting and throwing back a lot of liquor in order to get ready for action. Apparently Blanch DuBois, played by Vivien Leigh, had plenty of nights like this, but the point of this story is that Blanche is trying to get past that nature of promiscuous night life. She still has the hope of getting lucky; only now her use of alcohol is for the endeavor to destroy the guilt of her sinful past; and the dim light that constantly surrounds her is intended to hide the secrets of her sinful ways.
Blanche was looking for a different kind of luck however; she was looking for the luck of a new life with no ties to her notorious past. Blanche's routine steamy bathing habits reinforced this desire to begin a new life with the hopes cleansing away her sinful past. Blanche tried desperately to achieve the reputation of a respectable lady with her new romantic interest Mitch, performed by Karl Malden. However, Marlon Brando's character, Stanley, played the part of the light source that shown the brightest, most revealing spotlight on the true identity of Blanche in the effort to work against all of the deceit present in Blanche and Mitch's dimly lit dates. Stanley discovered the truth about Blanche's past, which put a whole new light on the face of Blanche DuBois in the eyes of her childlike Mitch. Blanche had been able to keep her secret in the dark long enough for Mitch to build up the desire to marry her. Nevertheless, Stanley caused Mitch's spark of love to become extinguished once the new light revealed the secret past of Blanche DuBois.
Blanche tramped onto the streetcar named Desire in the hopes to reach a more delightful place in her life, but her disreputable past was the cause of the twists, turns, and bumps on that journey. The abrupt stoplight in her path was Stanley, through playing the part of the spotlight, which led Blanche completely off the tracks from her desired destination.