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