When swindler La Spada and his accomplice José are released from jail in Madrid, they decide to pull a really great swindle: nothing less than to discover and sell a third picture of Goya's "Maya in Camison" (Maya in a nightgown). They engage the renowned Scorcelletti who lives in Rome and can forge any artwork. Afterwards, with help from the beautiful Eva, they convince celebrated art critic Francisco Montiel of the existence of a third Maya and let him find the picture. When the swindlers are at the point of selling the fake to an American millionaire, Scorcelli returns from Rome to sell one of his six other maya pictures.