AllMovie

A solid children's film with a breakthrough ecological message for the Czechoslovakian adults at this time, Tret'i Sarkan refers to the third spaceship sent to earth from the dying planet Lurida. Lurida is dying because the air, water, and land pollution went out of control. Hidden in a rocky outcropping known as Dragon's Rock, the buried spaceship is discovered by three boys while they set out to explore that area. The spacecraft was originally sent to earth in the Middle Ages to find out how the earthlings handle pollution, but being a little ahead of time, it waited. After the boys "fall asleep" they are taken to Lurida, where they see the devastating effects of environmental contamination. Fortunately, they do offer something to help the situation and get back to earth in time to warn the adults about their future prospects unless the environment is protected.