Bones and the Dinosaur Mystery by David A. Adler

Detective Jeffrey Bones is very good at solving mysteries. He has a detective's backpack full of useful things like walkie-talkies, notepads, and magnifying glasses. He always keeps it with him in case a mystery pops up.

Which is a good thing, because mysteries can appear in the strangest places - like in the museum Bones and Grandpa are visiting. Grandpa's friend Sally is with them, and Sally and Bones buy some neat dinosaur things at the gift shop. Bones really likes his blue plastic T-Rex.

But an hour later, after snacks and walking through the outer space exhibit, the T-Rex is gone! Detective Bones is on the case, and this time it's personal.