When the Aldens come across a robbery at an antique store, they decide to use their detective skills to help locate the stolen ruby ring, bracelet, and necklace. Yet, before their investigation even begins, someone breaks into the Aldens' home and steals a box of Benny's favorite Silver Frosted Star cereal! Is there a hungry thief on the loose or is something else going on? The Boxcar Children have another mystery to solve.