Put on your most colorful costume and travel to Venice, Italy, for an unforgettable festival filled with secrets and surprises. The Thea Sisters are incredibly excited to attend the famous Carnival, an annual celebration known for its elaborate dresses and beautiful, mysterious masks. They spend their days exploring the ancient city's narrow bridges, riding in gondolas down the water canals, and admiring the stunning outfits. But the joyful celebration is ruined when a sneaky thief begins striking right in the middle of the crowded parties. With everyone wearing disguises, finding the culprit seems impossible. The five sharp friends must work together, looking past the fancy masks to track down the clues. They have to catch the criminal and unmask them before the Carnival comes to a close and the thief escapes forever.