A number of swamp land men have died by strangulation and the inhabitants believe that an innocent man they hanged is seeking revenge on all of the male descendants of those responsible for his death. Maria, granddaughter of the innocent ferryman, decides to operate the ferry service. Chris Sanders, a son of one of the men who did the hanging, and Maria fall in love. The "strangler" seizes Chris and Maria offers her life if Chris is spared.

Wishing to dispose of his wife, psychiatrist Dr. Elliott makes his patient Nina think that she suffers from a compulsion to kill. He drugs Nina, murders his wife and leaves evidence that points to Nina. The latter, pre-conditioned by Elliott, also thinks she is guilty.