Malysh (1987)

When a spaceship lands on a deserted and inhospitable alien planet with no visible signs of alien activity the crew comes into contact with the only local inhabitant that seems to be around - a humanoid that looks remarkably human. It turns out it's a boy, who they come to call Malysh (Kid). He is in fact human - a lone survivor of a crashed spaceship some years ago, nourished and raised by an invisible alien civilization. Kid demonstrates inhuman abilities, learning to converse in human language in just few hours. The crew tries to use him as a medium to establish contact with the native civilization but things don't go the way they wanted... Based on novel by Strugatsky brothers "The Space Mowgli" this is faithful reproduction of the book - a stage play made for television.