This episode was similar to the Angels of the night episode. The strangular was expressing displaced aggression against older men. Since he could not express his aggression towards his father he satisfied his aggressive feelings over and over again on other older men by strangulating them. The last 10 minutes of the episode showed Harry's emotions and the motive behind his strangulations.
What kept me from rating this episode higher is the slow moving of the plot at the start and midway through the episode their cover is blown because the owner thinks his wife has hired detectives to spy on him and his business. I would have liked to have seen more of Harry's outbursts and possibly to attempt to coverup his strangulations from the Angels.