In the action-packed criminal case during the pre-Christmas season, friends Justus, Peter, and Bob must solve a mystery in the "The Three ??? Advent Calendar." Children aged 8 and up join the boys on their quest for the perfect Christmas gifts. Suddenly, events take a turn, and some strange coincidences begin to pile up. What is going on here? Together with their heroes, children open a door each day that contains a riddle, another clue, and a cool detective gadget to assist them in their search. Fully equipped, they get closer to the solution day by day. The three ??? must hurry - they only have 24 days left until Christmas.