After witnessing the violent death of her cousin, Catherine Holly (Elizabeth Taylor) is committed to a mental institution where, hoping to erase her "hallucinations" about Sebastian's death - and life -- Violet Venable (Katherine Hepburn), her rich aunt and the dead man's mother, asks brain surgeon Dr. John Cukrowicz (Montgomery Clift) to perform a lobotomy. For Cathy, fact and fiction meld into guilt-ridden nightmares about Sebastian's death. Yet, when under the influence of a truth serum she reveals every¬thing she knows about her deceased cousin, Cukrowicz's suspicions that the "hallucinations" actually happened are confirmed, causing Violet to lose her own grip on reality and leaving Cathy and the doctor free to pursue their feelings for each other.