There's a contest in Jigsaw's school to come up with a prize-winning invention. The kids are convinced the prize is a million dollars and everyone wants to win. But someone sneaky is messing up the contest. Jigsaw and Mila may have to invent some super-sleuthing gadgets of their own to solve this million-dollar mystery.
Jigsaw had this idea of how to invent somthing that you could hear other people talking when the door was closed. Someone stole the notebook that the idea was in and he has to figure out who did it. This is a fun chapter mystery that both of my children like to read these.