Ironside attends a hospital for psychological evaluation, and whilst he is tying knots in his psychiatrist's theories, it transpires that a crook is trying to use the situation to find out the whereabouts of a police informer. With Mark and Eve on holiday, however, there is just Ed to help the Chief, and a whole city to search through for clues.

After the murder of Police Captain Belding, his daughter, a rookie cop, is anxious to prove that the allegations of corruption against him were false. She hampers the Chief's investigations and generally gets in the way, but he takes a shine to her, and has her drafted onto the team.