Robert Browning's poem 'My Last Duchess' is a dramatic monologue narrated by the Duke of Ferrara, who speaks to an envoy about a portrait of his deceased wife. The Duke reveals his controlling and psychopathic nature as he recounts how he had her killed for not exclusively reserving her affection for him. Ultimately, the poem explores themes of art, power, and the Duke's moral decay, presenting him as a charming yet monstrous figure who values ideals over reality.