A hungry thief is on the loose in the classroom! Someone is sneaking into the lunch bags and stealing all the best snacks, from yogurt-covered raisins to mixed nuts and ginger snaps. The students are completely baffled, but luckily, the Invisible Inc. mystery-solving team is on the case. With Justin's sharp eye, Charlene's brave leadership, and Chip's secret advantage of being totally invisible, they are perfectly equipped to catch the culprit red-handed. Young readers will love following the clues and guessing the outcome in this funny, fast-paced adventure that proves no snack thief can hide forever.