When someone takes Justin's karate belt, his friends in Invisible Inc. try to determine a motive as they investigate the mystery.

Chip, an invisible boy, and his friends investigate the mysterious disappearance of yogurt-covered raisins, mixed nuts, and ginger snaps from their classroom.

Chip, an invisible boy, and his friends solve the mystery of who took the school ball from the playground

Frank and Joe are learning some awesome moves in karate class. But somebody steals Brian Ludlow’s black belt signed by action-movie hero Jimmy Han. Brian even

Three friends who call themselves "Invisible Inc." must solve a mystery when they receive a cryptic e-mail.