Strange things are happening in the apartment of Makar Veselov’s neighbor! The stern old man depicted in the picture leaves his “home” at night and walks from room to room... Alone, Makar would hardly have solved the mystery of the ghost from the portrait, but he gets down to business together with his older sister Sonya, brother Ladoshka and his pet - Honorik Po named Nyuk. That's who the detective's irreplaceable assistant is! It was Nyuk who was the first to break into the mysterious apartment. And the investigation began!..