Farewell, My Lunchbag: A Chet Gecko Mystery #3 by Bruce Hale
Danger may be Chet Gecko's business, but dessert is his delight. . . .
Chet Gecko's hunger for mystery is matched only by his appetite for cockroach casserole, mosquito marshmallow surprise, and stinkbug pie. So when the cafeteria needs help nabbing a food thief, Chet digs into the case with a passion he usually reserves only for dessert. But this time Chet may have bitten off more than even he can chew.
Someone has framed him, and now everyone at Emerson Hicky--even his trusted partner, Natalie Attired--thinks the food thief is none other than Chet!