Archie Lee Meighan, portrayed by Karl Malden, is a middle-aged owner of a cotton gin in Tiger's Tail County, Mississippi. He shares his life with his teenage bride, Carroll Baker, who goes by the endearing name Baby Doll, and her quirky Aunt Rose Comfort, played by Mildred Dunnock, in a run-down plantation house. The couple's marriage remains unconsummated; they sleep in separate rooms, with Baby Doll resting in an oversized crib, symbolizing the emotional distance between them. Despite Archie's fervent desires, Baby Doll maintains a firm boundary but has promised to surrender her virginity to him on her upcoming 20th birthday.
Tensions escalate as their financial woes worsen, particularly after the furniture company repossesses their belongings. The gin business is in shambles, with the local Syndicate Gin, managed by the ruthless Sicilian, Eli Wallach, monopolizing the cotton industry and putting Archie Lee out of work. During a celebratory gathering for the Syndicate, Archie Lee, driven by frustration, burns down his rival's gin house, prompting Eli Wallach to seek revenge, suspecting Archie Lee had a role in the fire since he was notably absent from the festivities.
The following day, Silva Vaccaro, played by Eli Wallach, brings his cotton to Archie Lee, igniting a sequence of flirtations with Baby Doll that raises her suspicions. In an effort to shield herself, she turns to Archie Lee, but he is too preoccupied with fixing his broken gin to offer her protection. Vaccaro then utilizes his own resources to procure a replacement part, continuing to pursue Baby Doll relentlessly.
As the situation intensifies, Baby Doll believes their home is haunted, a notion that Vaccaro exploits to disarm her. Their playful interactions shift dramatically when Baby Doll finds herself trapped in the attic, unable to leave until she signs a document accusing Archie Lee of the arson. Reluctantly, she does sign, but persuades Vaccaro to stay for a nap in the crib, an act that further complicates her loyalty to Archie Lee.
When Archie Lee returns, he is mortified to find Baby Doll and Vaccaro together in their home. Jealous and enraged, he seeks to reclaim his authority but instead discovers that Vaccaro is making advances in his business. In a tense dinner atmosphere, Baby Doll and Vaccaro mock Archie Lee, while he tries to reach out to friends for help against this threat.
Feeling humiliated and desperate, Archie Lee arms himself and searches for Vaccaro, but when the police arrive in response to Baby Doll’s call, the narrative takes a dark turn. They arrest Archie Lee upon discovering the affidavit she signed, leaving Baby Doll in a state of uncertainty about her future as she reconciles her feelings for both men.
As the evening winds down, Baby Doll faces a grim reality of what tomorrow may bring, leading Aunt Rose back into their dilapidated home with a heavy heart.
