Having received a family album as a birthday present, the girl realized that she was not in the children's photos. It turned out that she was not Olya, but Nadia, and her real mother disappeared a quarter of a century ago. Is her biological mother really dead for many years? How will a family detective story with murders, infidelities and mysterious disappearances end?

30 years ago, a woman gave birth to her fifth blonde-haired and blue-eyed baby, and brought home a dark-haired, black-eyed and seriously ill. All these years she was sure that her son was a stranger by blood. The mother of many children denies that she cheated on her husband, and believes in substitution in the maternity hospital. Did the mother of healthy children get her own or someone else's son?