Temponauts - two guys and two girls - go back in time for scientific purposes. However, there they unexpectedly encounter manifestations of the inexorable paradoxes of time, in violation of all prohibitions, they are forced to communicate with the great figures of the past and medieval swindlers, capture medieval castles and intervene in famous battles that changed the course of history. An alien guest unexpectedly appears on their spaceship - a time machine - and all of humanity faces the threat of complete destruction. Will brave temponauts be able to resist cruel time paradoxes and protect our blue planet? Will they be able to defeat love and personal feelings for the sake of saving all humanity?