Vincent Price is James Reavis who attempts to scam the U.S. out of the Arizona Territory. See the U.S. wants to be "fair". So they agree to honor any Spanish land grants. So Reavis finds an orphan girl, has her raised in the belief she's the Baroness Peralta. At the same time he travels across Spain. Forging ancient documents. Seducing poor foolish Gypsy girls and lonely Marquessas. And then he marries the young "Baroness" and files his claim for the Paralta claim...
A young Vincint Price almost makes up for the poor acting from the rest of the cast. Along with a very awkward flashback storytelling framing device. Though watching Price beat the hell out of Arizona vigilantes that try to strong arm him into giving up his claim is nice...