Timmy loves reading stories about great detectives, and soon he begins to spy mysteries all around his small Oklahoma town. Why was his next-door neighbor, the distinguished Dr. Moore, standing outside with a knife at midnight? Who's sneaking around their house, shining flashlights in the windows? And where did Mrs. Newberry's diamond necklace go? As Timmy and Doc work together to unmask the thief, Timmy also comes to understand the challenges Doc and his family face with his developing dementia, and discovers that a real detective needs a good heart as well as a sharp brain.