Otto's friend, Jim, has an uncle who runs his own detective agency. Jim dearly wants to be a detective when he leaves school, and decides that now would be a good time to start. Otto joins him in all kinds of activities related to being a detective, even though Otto is more interested in becoming a doctor when he is older. Otto's parents and his sister are often worried that the boys are up to mischief. They explain that if you want to be a detective, you have to observe and be aware of all that is happening in town.