 Harry has since made a way for himself in Chicago, straddling the world of the everyday and the supernatural by acting as a private investigator and consultant for the Chicago Police Department on seemingly unexplainable cases, and Bob is his secret weapon in this.Not only does Bob contain a wealth of knowledge gleaned from his own wizardly expertise, the ghost has accumulated centuries of experience since being tied to his skull.In addition, Bob can take on the appearance of people given a piece of their personage, an ability that has proven essential to the happy resolution of several cases (episodes 103, "Hair of the Dog;" 104, "Rules of Engagement").