My summary is NOT an indication that I disliked this episode. In fact, it was very good--one of the best ones of season seven. But much of the show has the doctor feeling very, very uncertain of himself and he mopes about...like a real weenie.
A big trial is coming up for a trial of a mobster. However, the mob boss' family is not about to let him be convicted. First, they kill the star witness. Second, at the same time, they conspire to make Quincy's testimony in the case involving the murder of the witness appear to be a mistake--and thus impeaching his credibility in the upcoming mobster case. At first, Quincy thinks he's really made a mistake and is uncharacteristically sullen. Then, when he realizes what's happened, he and Monahan spring into action.
Unlike too many episodes of the later seasons of "Quincy", this is NOT a social issues show that consists of Quincy preaching AT the audience. Instead, it's a return to the older and better episodes--ones which involve his investigating crimes! All in all, a very well written and entertaining episode--and a nice return to form.