Shortly before the New Year, the fates of two girls - Katya and Sonya - are intertwined in the most unexpected way. They are completely different: one lives with her younger brother in an orphanage, and the second lives with her oligarch dad and personal governess in a country mansion. But they have one secret for two. Through many adventures in New Year's Eve Moscow, clues left by Sonya's mother, a writer, lead them to unravel this mystery.