The first book in a series of short stories about a reverse werewolf. One day an ordinary boy Vasily Petukhov got a puppy. And on the full moon the puppy turned into an adult man. But this is such a naive, simple-minded and unlucky man that it is not clear which of them is an adult - he or Vasily. Moreover, 28 days a week he is just his own dog. But in the remaining three days, he manages to either get into a fight, or fall in love, or even fall into a deadly trap.