The team reopens a 1995 shooting case that has new evidence.
The team re-opens the 2004 case of a female veteran of the Iraqi War when her prosthetic arm is found in a river. Meanwhile, Scotty visits his older brother in connection with a case that brings up painful memories from their childhood.
When the remains of a sandhog miner who disappeared in 1947 are found in a subway service tunnel, the team is prompted to re-open the case when they suspect the victim might have been murdered for being a union activist.
A baby lost to SIDS turns out to have been drowned and the team must investigate to find the killer. Meanwhile, Ray is in the hospital and Lilly goes to take care of him.
Lilly and the team reopen a case involving an autistic boy who witnessed his parents murder in a car.
The team investigates the murder of legendary DJ Jimmy "The Hawk" Hawkins. Meanwhile Scotty talks to his brother again about childhood secrets.
When new evidence is found, Detective Jeffries' first murder case is reopened making Jeffries determined to close the case. Scotty continues dealing with his family issues.
When a bag of undelivered mail dating back to the 70s is found at the home of a dead postman, the team gets a lead on a cold case involving a missing girl from 1975. As they continue to investigate, their investigation turns from the brother of the young girl's best friend to the whole neighborhood as it becomes evident that racial tensions played a big part in the disappearance.
A handsome man finds overweight woman through a video dating service and takes advantage of them. One of them falls in love with him and in order to keep dating him, she helps him scam other women getting involved with murder which eventually leads to her own murder.
The detectives investigate the murder of one of their own. In the 60s an officer was killed when the force found out that he was gay. Lilly and team must find out if the officer was sent to his death by his own co-workers. Meanwhile, Vera steals a basketball from his neighbor who is annoying him. When the boy's mother shows up at the station, she lectures Vera and he ends up buying a new basketball and delivering it to them.
When Jeffries' former partner brings them a gun that was used in the murder of an out-of-towner, Lilly and Scotty have to go to Knoxville to investigate.
A video clip shows up on the Internet and gives new information to an underground fighting club that a young college boy was involved in before he disappeared. Lilly and the team use the Internet clip to try to discover what happened to the young man.
When a fingernail is found at a pool where there was an accidental death, Lily and Scotty re-open the case. The Williams family appears to be the perfect family, but as Lilly and Scotty investigate they find that the family was very dysfunctional.
Miller convinces the team to re-open a case from her undercover days that has haunted her for years. As Miller and the team investigate the two murders involving one wealthy girl and a less fortunate drug dealer, they realize that the connection between the two cases is methamphetamine.
An accidental fire is determined to have been caused by a bomb. As Lilly and the team investigate, they find that a yuppie couple was hosting a college reunion when they were killed. Lilly discovers that the group of friends at the reunion were part of a radical 70s activist group and the group has a secret that they would kill to protect. Meanwhile, the John babysits his grandson.
An adopted woman goes to Lilly asking her to investigate the murder of her birth mother, Hilary. The team investigates the home for unwed mothers where Hilary's mother sent her. The case becomes personal for Lilly making her think about her own relationship with her mother.
The body of a teenage boy who has been missing since the '80s is found leading the team to reopen the case. They uncover his secret love for dancing that got him killed. Meanwhile, Stillman tells Jeffries that there's a lead in his wife's car accident.
When a woman is found at the bottom of a river, the team is called in to investigate. They find out the woman was homeless and a mother of two. She was shot and the team must investigate to find out who killed her.
The detectives reopen a case dealing with the rape and murder of a young boy, when his father starts murdering sex offenders in retaliation for his son's death. Things get worse when Scotty gives information about the case to the father, leading the father to his son's killer.
An anonymous confession to the murder of a 16-year-old girl shows up at an art exhibit leading the team to reopen the case. Their investigation leads them to the politics of high school cheerleading and discover that the victim was killed when she tried to stand up for what was right and end the hazing the cheerleading team was condoning.
A great grand-daughter of a woman, Frances, who was murdered in 1919 comes to the team asking them to reopen the case. As the team investigates they discover that her murder had to do with her activism for women's rights and her defiance of her family. Meanwhile, Lilly has to get her drunken mother out of jail.
The FBI asks the team to re-open a cold case involving the murder of a longshoreman whose death might be related to a human trafficking ring the FBI is trying to bring down.
When a nurse confesses to six mercy killings, the cold case detectives re-open the 1998 case involving a terminally ill man who died while under the care of the nurse. But as the detectives investigate the case they realize there were a lot of people who wanted to see the man dead. However, the murder turns out to be a mercy killing, just not by the man they believed did it. Meanwhile, Lily struggles to help her alcoholic mother.
When an injured girl starts regaining her memory about the night her family was killed, the team investigates. Meanwhile, Lilly's mother dies while she's at work.