The only son of wealthy widow Violet Venable dies while on vacation with his cousin Catherine. What the girl saw was so horrible that she went insane; now Mrs. Venable wants Catherine lobotomized to cover up the truth.
Catharine Holly, a poor relation of a prominent New Orleans family, seems to be insane after her cousin Sebastian dies under mysterious circumstances on a trip to Europe. Sebastian's mother, Violet Venable, trying to cloud the truth about her son's homosexuality and death, threatens to lobotomize Catharine for her incoherent utterances relating to Sebastian's demise. Under the influence of a truth serum, Catharine tells the gruesome story of Sebastian's death by cannibalism at the hands of locals whose sexual favors he sought, using Catharine as a device to attract the young men (as he had earlier used his mother).