Три ключа из четвёртого "А"

Once upon a time, on the eve of the New Year, the Secret Santa disappeared…
Leia, Agasha, and Luka are just ordinary students of the fourth "A" class in the most ordinary school in the north of Moscow. Leia is engaged in figure skating and dreams of a dog, more precisely, a corgi; Agasha loves turtles, and Luka is a real chess genius. Two weeks before the New Year, something incredible happens to the kids: the "Secret Santa" sends Leia a key and a mysterious note with the word "SOS." The young detectives are sure it is a call for help, and the heroes begin their investigation!