Following a series of gunshots, Monte Beragon (Zachary Scott) collapses in the living room of a beach house, whispering the name "Mildred" before he breathes his last. His wife, Mildred Pierce-Beragon (Joan Crawford), soon arrives at the police station, visibly nervous and denying any involvement in her husband's murder. When authorities suggest that Bert Pierce (Bruce Bennett), her first husband and the owner of the murder weapon, is the prime suspect, Mildred defends him passionately, igniting the detectives' suspicions regarding her knowledge of the situation.
The narrative unfolds several years earlier when Mildred was married to Bert, living a comfortable middle-class life and devoted to her two daughters, Veda (Ann Blyth) and Kay (Jo Ann Marlowe). As Bert loses his job, tensions rise over Mildred's lavish spending on the girls, especially Veda, whom Bert accuses her of pampering. In mutual frustration, they decide to separate, a decision that profoundly impacts their daughters. Kay, the spirited younger daughter, is heartbroken over the departure of her father, while Veda, the more materialistic teenager, focuses on their dwindling resources and laments losing her luxuries.
In a desperate bid for financial stability, Mildred takes up a job as a waitress, quickly becoming adept but concealing her work from Veda, fearing her judgment. However, Veda uncovers the truth, setting off a chain reaction of disdain and contempt. Mildred, yearning for a brighter future, resolves to open her own restaurant with the backing of family friend Wally Fay (Jack Carson). Despite her endeavors, Bert's absence continues to haunt them, further complicated by a tragic pneumonia diagnosis for Kay, which tragically leads to her death.
Undeterred, Mildred channels her grief into her restaurant, which flourishes beyond her expectations. As her wealth grows, she showers Veda with expensive gifts, only to witness her daughter's entitlement and greed expand unchecked. In the midst of this, her relationship with Monte intensifies, revealing his ulterior motives as he exploits her fortune for his own gain. Mildred eventually leaves him but does so at the expense of her emotional connection to her daughter.
Veda's plot thickens as she claims to have eloped with Teddy Forrester, a wealthy young man, but soon reveals that her pregnancy announcement was a ruse to secure a hefty settlement from Mildred. This revelation leads to a violent argument between mother and daughter, resulting in Veda's expulsion from the house. Shattered and emotionally drained, Mildred retreats to Mexico for several years before returning only to find her daughter lost to her desires.
After a difficult reunion with Bert and her wayward daughter, Mildred's attempts to rekindle their bond are met with more disdain. In a desperate act to win her back, she seeks marriage with Monte, giving him a stake in her burgeoning restaurant empire. However, life takes a devastating turn during Veda’s birthday party when complications emerge due to Monte's mishandling of Mildred’s finances and his nefarious relationships.
In a heart-wrenching climax, Mildred discovers Veda and Monte together, only to find that Veda's calculated manipulation has led her to the darkest of actions. Upon confronting Monte's rejection and Veda's explosive rage, the story takes a tragic twist as Veda fatally shoots Monte out of jealousy and betrayal, gasping Mildred's name as he dies.
Returning to the scene of the crime, Mildred grapples with her daughter's dark fate while she weighs her final options. Her love for Veda clashes with the grim reality before her, leading to a decisive moment as Mildred opts to call the police. In a final act of cruelty, Veda is arrested, leaving Mildred to confront her past with Bert as they walk away together, seeking to leave the tragedy behind.
