A deranged ex-cop has planted a bomb in the city and will only give the location to Nash is Nash kills Joe. Meanwhile Nash must also handle bringing Harvey a new partner, evicting Joe and Inger, and Cassidy's first day on duty. Inger and Joe purchase a house that seems to good to be true.
Nash investigates a series of robberies committed by an organized group targeting wealthy people. Joe seeks help in stopping a neighborhood speeder. Meanwhile Joe takes a side gig to find a missing cat on top of a gig Nash takes on to solve the mystery of a pregnant nun claiming immaculate conception.
Nash accidentally stumbles upon a group of Marine's who've stolen D.E.A. property, lead by an ex sergeant of Babcock's. Harvey finds out Babcock has yet more secrets that have been kept. Nick sets up Nash on a blind date with his lady's daughter, whom has more going on than meets the eye. Joe has troubles with his contractor.
Nash and Joe find not only themselves but their private investigators business impersonated. Harvey finds himself as the deciding vote in the neighborhood over a contentious issue. Cassidy investigates the supposed accidental death of a young college man.
Nash and Joe investigate a group of men killing each other to score points in a real life video game battle. Boz seeks Nash's help to clear himself of a murder charge, which also leads to surprising discoveries about Boz.
Tony B is supposed to be dead, but his funeral leads Nash back to an old nemesis and blast from his past. Nick gets arrested for protesting the impending demolition of a building. Cassie goes on the hunt to find why this building is so important to Nick and how it ties into his past. Joe is accused by Inger of using marijuana, and Ulla is to blame. We find out about Nash's grandmother.
Nick tells Nash he thinks his son, Bobby is back and following him. They think he's missing in action in Vietnam but Nash knows he's alive and is in the drug business in Southeast Asia. Nash sees someone following Nick but it's not his brother, he's too young but he does look like his brother in his youth. Someone pulls a gun on him so Nash intervenes. He learns the one with the gun works for a drug dealer who also operates in Southeast Asia. Nash finds the young man and talks to him learns that he is the son of Nash's brother. And that his father and the other drug ...
Nash and company track down a serial killer who picks people up in a cab; Rachel reveals the truth about what she's been up to at the SIU; and Cassidy debates whether she wants to be a cop anymore. Though not officially advertised at the time of airing, this was the series finale.