The Heart of a Dog recap

A starving Moscow stray named Sharik is rescued by the eminent surgeon Philip Preobrazhensky, who implants in him human organs taken from the dead criminal Klim Chugunkin. The dog rapidly becomes a man calling himself Polygraph Sharikov, but gains speech and legal standing without maturity or self-control. Encouraged by the housing chairman Shvonder, he claims space in the professor's apartment, embraces official slogans, behaves destructively, and obtains work killing stray animals. His attempt to marry a young colleague collapses when Preobrazhensky reveals his origins. Sharikov then denounces the doctors and threatens them with a gun. Preobrazhensky and Bormenthal subdue him and reverse the operation. Investigators find no murdered man, only Sharik returning to canine form. The dog resumes a comfortable life in the apartment, while the professor continues his research.

A stray dog suffers from hunger and a badly scalded side while wandering wintry Moscow. He distrusts most people but follows a well-dressed man who buys him sausage and seems able to read his condition at a glance. The man is Professor Philip Preobrazhensky, a prosperous surgeon with a large apartment that also serves as his clinic. He brings the dog home, has his staff treat the wound, names him Sharik, and feeds him until the animal accepts the household as a refuge. Preobrazhensky's clients come for expensive rejuvenation procedures. His secure way of life is challenged by Shvonder and other members of the building's housing committee, who demand that he give up rooms. The professor defeats the demand by calling an influential patient, demonstrating that his connections protect privileges the new committee wants to redistribute.

Sharik recovers and settles into the professor's comfortable routines, observing meals, patients, and Preobrazhensky's contempt for disorder imposed in the name of social reform. The apparent rescue has a hidden medical purpose. Preobrazhensky and his assistant, Dr. Bormenthal, prepare Sharik for an unprecedented operation and replace the dog's testes and pituitary gland with organs taken from a recently dead man. They expect the procedure may illuminate rejuvenation, but Sharik nearly dies during the surgery. The doctors can only wait to see what effect the transplant will have.

Bormenthal's clinical notes record an astonishing change: Sharik loses fur, grows, begins walking upright, and acquires human speech. The donor is identified as Klim Chugunkin, a dead thief and balalaika player with a record of drunken violence. The transformed creature displays habits and language associated with the donor rather than the elevated human nature Preobrazhensky hoped to uncover. Calling himself Polygraph Polygraphovich Sharikov, he demands identity papers and registration in the apartment. Shvonder helps him assert these rights and supplies political language that sharpens his conflict with the professor. Sharikov remains impulsive and destructive, creating household disasters while insisting that the doctors treat him as an equal citizen.

Attempts to educate Sharikov fail. At dinner he repeats slogans without understanding them and proposes dividing property, while rejecting the discipline Preobrazhensky says must accompany social standing. His drinking, crude behavior, and pursuit of women make life in the apartment increasingly dangerous. He disappears and then returns with excuses for the trouble he has caused. With Shvonder's assistance he obtains a government post directing the removal of stray animals from Moscow and gains power by applying his old canine hostility toward cats as official work. He brings home a young typist and claims she is to marry him, having concealed his origin and intimidated her. Preobrazhensky exposes the truth and sends her away. Sharikov retaliates by submitting a denunciation against the professor and Bormenthal.

Sharikov returns after his denunciation and, when ordered to leave, draws a revolver. Preobrazhensky and Bormenthal overpower him. They conclude that instruction cannot repair the result of the experiment, and the professor surgically removes the transplanted human tissue. Sharikov disappears from public view as his body gradually returns to canine form. Police and officials search the apartment on suspicion that the doctors murdered him, but Preobrazhensky produces the living, doglike Sharik and maintains that the operation itself explains the transformation. With no corpse and no clear crime to prove, the investigators withdraw. In the epilogue Sharik again lives contentedly as the professor's pet, unable to comprehend what happened to him. Preobrazhensky retains his home and resumes medical work with Bormenthal, ending the experiment where it began but without erasing what it revealed about its creators and their society.

After Sharikov reports Preobrazhensky and Bormenthal to the authorities and then threatens them with a revolver, the two doctors overpower him. Preobrazhensky performs another operation, removing the transplanted human tissue. When investigators arrive to inquire into Sharikov's disappearance, the professor presents a living creature who is steadily reverting to canine form; the officials cannot prove that a murder occurred. In the epilogue, Sharik is once again a dog living contentedly in the professor's apartment, with only fragmentary discomfort associated with his earlier transformation. The building committee has not displaced Preobrazhensky, and the professor resumes his surgical work with Bormenthal. Sharik watches without understanding as another human brain is examined, leaving the household outwardly restored while the experiment's ethical consequences remain with the reader.