Chip, an invisible boy, and his friends investigate the mysterious disappearance of yogurt-covered raisins, mixed nuts, and ginger snaps from their classroom.
The invisible boy Chip intends to enter his invisible dog Max in the dog show, but when Max goes missing, Chip and his Invisible Inc. friends suspect foul play.
Brian and his younger sister Penny become involved in a mystery at the science museum where they are working on a woolly mammoth display for a science fair.