Vincent Price plays Gallico the great, an inventor of stage-magic effects who aspires to become a star in his own right. Just before his first performance, his act is shut down by capricious manager Ormond who wants Gallico’s brilliant buzzsaw effect for the act of the Great Rinaldi, an established star. With this defeat, and the humiliation of having already lost his wife Claire to his rival, Gallico goes insane and uses the buzzsaw to decapitate his manager.

In the Fifteenth Century, France is a defeated and ruined nation after the One Hundred Years War against England. The fourteen years old farm girl Joan of Arc claims to hear voices from Heaven asking her to lead God’s Army against Orleans and crowning the weak Dauphin Charles VII as King of France. Joan gathers the people with her faith, forms an army and conquerors Orleans. When her army is ready to attack Paris, the corrupt Charles sells his country to England and dismiss the army. Joan is arrested, sold to the Burgundians England and submitted to a shameful political trial in Rouen castle.

When Dr. Anthony Edwardes arrives at a Vermont mental hospital to replace the outgoing hospital director, Dr. Constance Peterson, a psychoanalyst, discovers Edwardes is actually an impostor. The man confesses that the real Dr. Edwardes is dead and fears he may have killed him, but cannot recall anything. Dr. Peterson, however is convinced his impostor is innocent of the man’s murder, and joins him on a quest to unravel his amnesia through psychoanalysis.

The bloody hostility of two noble families on Corsica determines the destiny of two brothers who were divided – as Siamese twins born, successfully operated and apart grown up – by the love to a woman. In the revenge against the murderers of her parents they join.