It's off to Italy for Mimi and Papa and their two grandchildren, Christina, 10 and Grant, 7. Mimi, a children's book writer, is writing a new mystery set in Italy, and Papa is going to visit an old friend. It doesn't take long for a mystery to unfold as Christina discovers a puzzling advertisement in an Italian newspaper... and suspicious men in black trench coats! Follow Christina and Grant, and their two new friends, Luigi and Francesca, as they look for clues while exploring Italy on fast scooters and floating gondolas. Things get even more interesting as the kids end up in the middle of Carnivale holiday festivities!