The film is set in Moscow not long after the October Revolution where a complaining stray dog looks for food and shelter. A well-off, well-known surgeon Phillip Phillippovich Preobrazhensky happens to need a dog and lures the animal to his big home annex practice with a piece of sausage. The dog is named Sharik and well taken care of by the doctor's maids, but still wonders why he is there. He finds out too late he is needed as a animal testing: the doctor implants a pituitary gland and testicles of a recently deceased alcoholic and petty criminal Klim Chugunkin into Sharik.