Irena (Simon) is an immigrant from the Balkans who believes in a curse that will change her into a deadly panther who must kill to survive. So she won't consummate her marriage to Oliver (Smith). When he confides her troubles to co-worker Alice (Randolph), Irena's jealousy precipitates her transformation as she stalks Alice. A classic among the horror genre with unrelenting terror from beginning to end, especially since the metamophosis only suggested. First horror film from RKO producer Val Lewton.