During the 1880s in India, a young orphan named Kim (Dean Stockwell) is employed by Mahbub Ali (Errol Flynn), an English spy who masquerades as a horse trader. Kim meets a Tibetan lama (Paul Lukas) and agrees to help him find a sacred river. When it is discovered that Kim has British ancestry in his blood, from his father, he is sent to school. Ali, however, is convinced that the boy has the makings of a great spy. Now educated and trained, Kim has a lot of responsibility thrust upon him.