The film tells about the concept of stress, proposed by the Canadian scientist of Hungarian origin G. Selye. The reactions of various animals to the action of various natural stresses are shown. 1st part. A herd of horses moves in a circle in the paddock. Laboratory staff at work at the University of Budapest. G. Selye in the laboratory with teachers and students. G. Selye gives autographs to students. Newsreel footage: G. Selye meeting with teachers and students of the University of Budapest; G. Selye makes a report (synchronously in Hungarian). Horse with a foal in the meadow. The foal is trying to get to his feet. Fox with cubs near the burrow. Raccoon in the clearing. The fox runs around the raccoon trying to bite the raccoon. The raccoon breaks out of the fox's clutches. Fox cubs in the hole. Fight of a fox and a wolf. 2nd part. Deer in the meadow. Fawns. Deer fight. Roosters in the pen. Fight of roosters. Monkeys among the branches of trees. A flock of monkeys in the meadow and near the lake. Crocodile swims on the lake. Monkeys fearfully move along the shore of the lake, shout, wave their arms, throw sticks and stones into the lake. The deer runs in the paddock. The deer moves slowly across the field. The monkey is eating a banana. 3rd part. Monkeys in the meadow. Excited monkeys scream and jump in the clearing. Race at the hippodrome. Polar landscape. Penguins. Drifting snow. Penguins, clinging to each other, move in a blizzard. Penguins with cubs. The penguin screams around the dead cub.