The plot's central tension revolves around the secret of the $10,000 hidden inside Pearl's doll. After marrying Willa, Harry Powell's frustration grows as he fails to extract the secret. During a chillingly stylized bedroom scene that resembles a chapel, Willa, having realized Powell's true nature and lack of interest in her, tells him she understands he married her for the money, not for love. Powell then murders her with his switchblade. The subsequent underwater sequence, showing Willa's body sitting in a car at the bottom of the river, her hair waving like seaweed, is one of the most indelible images in cinema history.
Powell convinces the townspeople that Willa left him for a life of sin. After he finally learns the money is in the doll, the children make a desperate escape, fleeing down the Ohio River. Their journey leads them to the farmhouse of Rachel Cooper, a tough, devout woman who cares for stray children. Powell eventually tracks them there, leading to a tense, psychological standoff. The climax is not a physical brawl but a battle of wills and faith, with Rachel standing guard all night with her shotgun while Powell waits outside, singing his haunting hymn. He eventually breaks in but is shot and wounded by Rachel, retreating to the barn where he is apprehended by police the next morning. The townspeople who once revered him quickly form a lynch mob, but Rachel protects Powell from them, understanding the cycle of hate. In the end, John and Pearl are safe, having found a true protector, and John is finally able to let go of the burden of the money.