The speaker shows his listener a portrait of his late wife, the Duchess, painted on the wall of his home. He notes the lifelike quality of the portrait and how it seems to ask how the painter captured her intense gaze. The Duke questions why the portrait depicts the Duchess with a "spot of joy" in her cheek, implying it was not just his presence that caused it. He suggests the painter, Pandolf, made flattering comments that made her blush, which the Duke saw as inappropriate given she was his wife. This reveals the Duke's desire to control his wife and his jealousy that led to her becoming his "last" Duchess.