A mystery unfolds in class 3C. Many students' snacks mysteriously disappear from the classroom. Food thefts become increasingly frequent, and among the students, excitement gives way to nervousness and furious protests. Chicco decides to take matters into his own hands and, assisted by Bruno, launches into a thorough police investigation to track down the culprit. Naturally, Chicco and Bruno seem unlikely to be playing Sherlock Holmes and Dr. Watson.