Penniless Leonard Outram attempts to redress the undeserved loss of his family estates and fiancee by seeking his fortune in Africa. In the course of his adventures he and his Zulu companion Otter save a young Portuguese woman, Juanna Rodd, together with her nursemaid Soa, from slavery. Leonard and Juanna are plainly attracted to each other, but prone to bickering, and their romance is impeded by the watchful and jealous Soa. The protagonists seek the legendary People of the Mist, said to possess a fabulous hoard of jewels.