Mannion has to handle an international crisis after the son of the Colombian ambassador is discovered to be the main dealer of the heaviest type of heroine yet. Threatened not to do anything about it, Mannion studies the international code for diplomatic immunity and plays around until he gets Eduardo kicked out of school and arrested. Meanwhile, Temple helps a heroin addicted woman; Ella has problems with Ricky after he returns from summer camp; Jack Jr. goes to court for his drug problem and Nancy finds Jack a new assistant.

Mannion faces off with Putin once again and the stakes are even higher when Putin resurfaces and kidnaps Mannion's daughter! Mannion's initial theory is that Putin wants to trade one daughter for another, but everything changes when the CIA informs Mannion that Putin's daughter, Erin, has disappeared from the Witness Protection Program. Mannion finally finds his dazed and confused daughter, Beth; however, things get more complex when the police find a dead woman, believed to be Erin, in Beth's car trunk. As Beth is arrested for murder, Mannion must prove that his daughter is being set up and the only person who can help him is Putin.

After a man crashes and dies and the police finds thousands of dollars with him, Mannion and his men start an investigation to prevent the dead guy's old girlfriend from being killed. Turns out an old shooter that killed one of Mannion's friend back in New York years ago is the hired killer they're looking for, and the woman they were protecting was behind the plan to kill her current husband and keep the money. It's Jack's second and final chance to catch the guy. Mannion hires a personal wedding dress designer for Ella, who has second thoughts about her marriage. Nancy is diagnosed with Huntington's disease after falling from a fire escape and suffering a concussion while chasing a criminal.

One of Vanessa Cavanaugh's students commits what she taught to be a perfect murder. No evidence, no witnesses. After the murder confesses to Temple and Debreno his crime, he starts to play with Mannion, who can't seem to charge him since the confession wasn't recorded. Mannion is out to get him for the murder of the father of 3 children and ends up finding a way to link the suspect to the murder scene. Meanwhile, Parras works on a Jane Doe case and finds the victim's estranged mother; and Kendall finds it difficult to end her relationship with a married man.

After a video where Brander arrests a drug addict is made public and turned into a abuse of power issue, the Mayor demands that Mannion fires Brander, which he refuses to do giving that the man was found innocent. Instantly, a major riot breaks out in the city, with the citizens protesting and attacking the police, demanding that Brander gets fired. Several police cars are bombed and set on fire, and Nancy rescues an officer from an angry riot. He's badly injured, and asks her out when he comes by to pick up his dog. Meanwhile, Temple witnesses his friend Reese die while trying to find the man who shot him. Mannion is trying to save Brander, but when he can no longer live with his guilt he turns in his badge. Unfortunately, the mayor taped Mannion's conversation with Brander over the phone and fired him for obstruction of justice. Late at night, Clive calls him up, saying that Ella died unexpectedly.