The series "Posrednik" is a Soviet science fiction action film based on the novel "High Noon" by Alexander Mirer. A mysterious gigantic sphere of extraterrestrial origin hangs in the sky above Earth. Soon, uninvited guests begin to attack. They send their super-technological weapon, the Posrednik, to the city. It can take control of the mind of any person and turn them to the side of the invaders. However, the Posrednik has a weak point - it does not affect children and mentally unstable individuals.