Rex wants to play, but other animals (the cock, the pig, the goose, the turkey) don’t understand his bark. Rex decides to learn the languages of the animals on the farm. He joyfully gobbles, oinks, crows, honks, moos, and bleats.

Rex is glad to see his master, a hunter. The dog has already made friends with the bunny, so he will do his best in order to save his friend. Rex protects small animals.

Rex wants to become a painter. The dog’s painting showing an abstract cock is appreciated by a strange painter. He takes Rex to a gallery. The doggie gets a diploma and sells the painting for a sausage. As a great painter, Rex is kidnapped! He will break free... using a brush.

Rex is a witness of an accident - a dog was hit by a car. Rex transports it to his own place using a pram, he puts a cast on its paws and prepares some wheels for a walk. When Rex feels that his patient is OK, he asks a cat to attack the dog. Rex wants to make it run.

Rex and the cat are friends. Unfortunately, the cat wants to hunt the bird – a friend of Rex. In order to prevent that, the dog and the bird prepare some traps for the cat, they use a bucket of cold water and a rubbish bin.

Hens ask Rex to investigate the case of their missing eggs. The dog catches a fox red-handed. He follows the traces of the fugitive. It turns out that the fox breeds chicks in its cave. Rex finds the pit and frees the chicks.

Rex, influenced by music, begins to sing. He can recognize a harmony of sounds. The dog decides to sing by the window of a neighbor who plays the piano beautifully. She is better than a boy whose violin is out of tune. However, playing with a stick is not so great when you are a singer.

Rex and his master (a boy) read a mushroom atlas together, then they set out for the forest. The dog is very careful, sniffing for edible mushrooms. After some time, he finds a huge boletus. Rex can’t believe his eyes – there’s a dwarf underneath a toadstool. A storm blows up, the friends go home.