Mannion attempts to stop a gang war and ensure the release of two officers held captive by one of the gangs. In other events, Temple suffers the effects of smoking crack while undercover as a drug dealer and Ella receives a marriage proposal.

Debreno's past is used against him by a defense attorney bent on discrediting him in a case involving a diplomat's son arrested for dealing drugs.

Mannion tries to stop the execution of a man falsely accused of murder when a priest receives an anonymous letter revealing the whereabouts of the murder weapon. In the meantime, Ella struggles with whether to let Ricky visit his father in prison.

Mannion asks Agency director Tom Gage for information about the murder of a CIA agent who was working undercover, then questions Lisa Fabrizzi, who was the last person to see the victim alive.

Mannion is pressured to reinstate a politically connected police commander he just demoted for his poor job performance, while Nancy is faced with possible discipline for injuring a suspect with her nightstick.

Mannion investigates the theft of a $2 million Picasso painting from a local museum. In other events, Clive tells Ella a secret when she suspects her cancer is back and Nancy learns her mother is getting divorced.

Mannion's friend and restaurateur Teddy Reed is the only witness to a Congressman's murder, and Mannion suspects she's lying about the whole situation. Meanwhile, the city erects a statue depicting a heroic act by three police officers, including Cutter. But many are infuriated when Cutter's figure is altered to represent someone of a different race.

Mannion faces 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. When Beth is arrested for murder, Mannion must prove that his daughter was framed. The only person who can help him is Putin. Also, Mannion and Parras remember Mcgregor one year after his death.

A teacher, protesting the Board of Education's inattention to her cries, takes the board hostage at gunpoint, and Mannion must diffuse the situation. Frustrated by getting the run-around from the board and environmental agencies, she gives Mannion 12 hours to find answers to the teacher's and students' health problems before she opens fire. Mannion and his team must uncover a complex environmental cover-up while keeping the board and the teacher alive. Meanwhile, Ella asks Clive, the new man she is seeing and a lobbyist for the chemical industry, to look into the case from his end.

Page and Debreno investigate the murder of a reporter discovered in an abandoned building. Evidence points them to a man who uses a wheelchair and claims the victim was already dead when he found her. Mannion goes to NY for his daughter's graduation from the police academy and has difficulty saying goodbye to Sherri. Ella goes to Ricky's school to check why he has problems with his new teacher and finds out she looks just like his late mother. Meanwhile, Parras meets a charming man in a cab and thinks he might be "the one," while Brander confesses his love for her.
 

After the vandalization of a mosque, Mannion questions the mosque president, who reveals that the mosque has been receiving threats. Meanwhile, Temple and Debreno investigate two other hate crimes - both with similar scenarios - involving a rabbi and an African-American, respectively. Now, before racial and ethnic tensions escalate, Mannion and his team must get to the bottom of these crimes - unaware that the perpetrator is the last person they would suspect. 

A Russian woman claims that Mannion's nemesis, Dimitri Putin, is trying to kill her and that Putin ordered her husband to murder McGregor. She also claims there's a hidden recording of Putin giving the order to kill the chief, so Mannion races to find the evidence, only to come face to face with his enemy.

When police officer Robert Turner woke up one Thursday morning, he thought it would be just a normal day on the force. However, when a car plunged off a bridge into a river, Turner lost his life rescuing the family inside. Now, Mannion and his team reflect on the life and death of one of their own.

A woman claims to have been raped by a police officer who pulled her over for a traffic violation. While searching for the bad cop, Mannion is visited by his daughter, who has news about her future.

Mannion goes after a ring of thieves who steal expensive purses and sell them on the black market after a woman is killed in one of their attacks. The chief must also deal with an ex-girlfriend who claims partial ownership of his boat.

After Nancy discovers a murdered homeless man, Mannion notices that the body has a distinct military tattoo. He identifies the man as a former Marine believed to have been held prisoner in a Vietnamese camp. They soon learn that the victim may have been one of many POWs returned to the United States in the 1980s after the government stated that there were no prisoners left in Vietnam. As Mannion delves further into the case, he must battle the demons that continue to haunt him from his time in Vietnam. 

A seven year old boy shoots two of his fellow students with a gun that was confiscated in a buy back program. Meanwhile, Temple thinks a friend might be on drugs again and a woman puts a curse on Mannion for arresting her husband.

A construction worker finds the skeleton of a dead boy. He was Noland's last case before being promoted - a case that was never solved. Now Noland devotes all his efforts to putting an end to this crime. They finally arrest the boy's mother, who also killed another son of hers. Meanwhile, Mannion tries to change the child abuse scenario in the city. Nick negotiates a possible candidature of Mannion's for the upcoming mayor election. Ella has to fire an old employee but manages to keep him. Parras has trouble dealing with an abusive father that reminds her of her own father until proven that this father never touched his problematic 14-year-old son.

After a woman is stabbed to death outside her apartment building, and no witnesses are willing to speak to the police, Mannion moves in, hoping to gain the residents' trust. The housing project has been a dangerous place to live for a long time, and the residents are wary of the police, who never seem to be there when they need them. Now, Mannion must convince them that this is not a media stunt - he honestly wants to make their lives safer - and that they need to speak up before the killer strikes again.

Temple and Debreno are working on a carjacking followed by a murder case. Parras is suspicious when the victim's fiance cries, but no tears come from her eyes. The case is only solved with the help of a schizophrenic homeless man with multiple identities, who saw the suspect with another man just before the shooting. Temple and Debreno are not getting along, and Mannion has to interfere before Temple (who's much more religious since his fiancee's death, which annoys Debreno) tries to quit. Ella has to handle a strike/budget crisis. Parras is back on the streets, and her partner takes it hard when another black man insults him. A snake is left loose around the office.

Mannion has to handle an international crisis after the son of the Colombian ambassador is discovered to be the primary 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 and his team come under fire from the African-American community when an affluent white woman disappears at the same time as a black woman with a drug habit. Debreno is introduced as Temple's new partner, who is still recovering from the deaths of his fiancé and his ex-partner. Ella is back at work, still recovering from breast cancer. Nancy considers going back to the streets as she recovers from Danny's death.