Because of the suddenly started ice drift, the boy Sergey and his faithful old dog Rex turned up on different ice floes, after which the dog rushed after the master into the water and helped the ice-floe to hit to the shore. Rex himself was dragged out of the water with great delay, did not suffer pneumonia and died in the hospital where he was taken. The boy's parents asked the veterinarian Valerian Valeryanych not to inform his son about the dog's death - the father intends to do it himself, but he remains silent for too long, as Rex meant too much to the boy.