The Duke of Ferrara shows a visitor the portrait of his late wife, and in a monologue of fifty-six lines reveals that he had her killed for being too easily pleased, too democratic in her affections. Browning invented the dramatic monologue with poems like this, creating speakers who condemn themselves without knowing it. The rhyming couplets are conversational, the menace gradual, the final lines about dowry negotiations chilling in their casualness. The Duke sees nothing wrong with what he has done. That is the horror.