Legend of the Lost (1957)

Paul Bonnard arrives in Timbuktu in search of a guide to escort him into the Sahara desert. American Joe January takes the job despite misgivings about Bonnard's plans. Dita, a prostitute who has been deeply moved by what appears to be Bonnard's spiritual nature, follows the two men into the desert. Eventually the trio arrives in the ruins of a lost city, where Bonnard hopes to find the treasure his father sought years earlier before disappearing. But what Bonnard finds alters him in unexpected ways, with tragic results.