The team reinvestigates a 1995 shopping mall massacre committed by two 16-year-old boys, Neal Halon and Cameron Coulter, who committed suicide at the scene, after the discovery of new video evidence in an air shift points to a third shooter.

The team reopens the 2004 case of Dana Taylor, a missing 30-year-old Iraq War veteran, wife, and mother, after her prosthetic arm is found in a river. The team learns that the victim was struggling to reintegrate into civilian life after losing her arm in her last tour.

The team reopens the 1948 disappearance of John "Boomer" Donovan, a missing sandhog miner, after his remains are found in a subway service tunnel. The team discovers that the victim was an outspoken unionist following the death of his best friend, and his activism ruffled a few feathers.

The team reinvestigates the 1982 death of Iris Felice, a newborn baby girl whose death was originally reported as Sudden Infant Death Syndrome. New evidence, however, suggests that she may have been murdered.

The team reopens the 2003 double-murder of Steve and Lisa Harris, the parents of an autistic boy, after Lilly's boyfriend brings her information suggesting that the boy might have witnessed the murder. The team discovers the boy was a victim of bullying and discrimination due to his autism, and the parents’ efforts to accommodate him may have led to their deaths.

The team reopens the 1958 death of John "The Hawk" Hawkins, a popular disk jockey, after discovering audio evidence indicating that his death may have been a murder staged as suicide. The team uncovers a complicated relationship with the victim and a young girl as well as his station's less than savory practices.

The team reopens the 1979 murder of Libby Bradley, an upper-class housewife and schoolteacher, when her bloodstained jacket is found in a tree in the woods where she was stabbed to death. The team soon discovers that the victim was having marital problems with husband Carl that affected even their own daughter Helen, whom Jefferies had promised that he would catch her mother's killer.

The team reopens the 1975 case of Melanie Campbell, a missing 8-year-old girl, after an undelivered letter of hers is found. The team sets out to determine the fate of the girl, and in doing so, delves deep into her controversial relationship with her African-American neighbor and the racial tensions in her neighborhood.

The team reopens the 1989 murder of Martha Puck, a 33-year-old single woman, after her video dating tape shows up in the apartment of a man who committed suicide. The team learns that the man was a con artist who was working with the victim to commit various crimes.

The team reopens the 1968 murder of Sean Cooper, a young policeman with a "cowboy" reputation who was shot to death in his patrol car, after a terminally ill convict claims the cop was crooked. The case takes a shocking turn after the team learns that the victim was having an affair with his partner.

The team reopens the 2000 murder of Truck Sugar, a country singer who was on the cusp on his big break, after the murder weapon turns up. Lilly must travel to Tennessee with a reluctant Scotty in tow to reinvestigate the case.

The team reopens the 2006 case of James Hoffman, a gifted missing 17-year-old boy, after a video clip of him is found on the Internet by his sister. When the victim's remains are found, the team zeroes in on his school and discovers a very cutthroat environment behind closed doors.

The team reopens the 1996 death of Lauren Williams (Donna Mills), who drowned in her ex-husband's pool during a power outage. The drowning was originally ruled as accidental, but the discovery of the woman's fingernail underneath the diving board suggests she may have been held under. The team learns that the victim had a twisted relationship with her family, particularly her son.

The team reopens the 2002 murders of Skill Jones and Madison Reed, two teenagers from different parts of the city, after Kat discovers they were both fatally shot at precisely 8:03 AM. The team discovers that the timing of their deaths wasn't the only connection as both teens were involved in drug dealing.

The team reinvestigates the 1981 deaths of Jack and Johanna Kimball, a married couple who died in a house explosion, after remnants of a bomb are found during the remodeling of their house. The team soon learns that the couple was haunted by a secret from their past anti-war activism, and their investigation leads to a shocking discovery.

The team reopens the 1964 murder of Hillary West, a 17-year-old girl and young mother who was killed hours after giving birth to a baby girl in a church-run home for unwed mothers. The team learns that the home was harboring some dark secrets.

The team reopens the 1984 disappearance of Maurice Hall, a 16-year-old boy who was written off as a runaway, after his remains are discovered in a dumpster, with an autopsy revealing he was bludgeoned to death. The team learns the victim was an aspiring dancer who wanted to follow in his late mother’s footsteps, much to the dismay of his father and older brother, while also getting caught in a love triangle.

The team reopens the 1999 disappearance of Marlene Bradford, a widowed mother of two, after a station wagon containing her bones is found at the bottom of a lake. The team learns that the family was living in their car after the patriarch's death.

The team reopens the 1987 rape and murder of 6-year-old Clayton Hathaway after his father Mitch, who was convicted of the crime, is released and pushes a sex offender from the roof of a building, vowing to systematically kill a new offender each day until his son's real killer is found. During the investigation, one team member makes a poor call that threatens to derail the case.

• Song featured in the intro: "Bizarre Love Triangle", by New Order.
• Song featured in the finale: "Never Surrender", by Corey Hart.

The team reopens the 1997 death of Rainey Karlsen, a 16-year-old cheerleader who was thought to have died from an accidental drug overdose, after an anonymous confession to her murder is found in a modern art exhibit along with new suspicious evidence. The investigation uncovers some of the cheerleading squad's dark secrets.

The team reopens the 1919 murder of Frances Stone, an 18-year-old heiress, at the request of her great grand-niece who heard about Lilly from a women's studies lecture. The team discovers that the victim was a suffragette, which put her at odds with her family.

The FBI asks the team to reopen the 2005 murder of 35-year-old longshoreman Mike Chulaski, whose death might be related to a Russian human-trafficking ring that the FBI is trying to bring down. The team discovers that he may have been killed by the leader of the ring for trying to rescue a young girl from the group.

The team reopens the 1998 murder of Jay Dratton, a terminally ill businessman, after one of his nurses confesses to six incidents of mercy killing. The team discovers that the victim had made many enemies throughout his career, including members of his own family.

The team reopens the 2006 triple homicide of the Jacobi family (parents Adam and Emily, and their son Stewart) when the sole survivor of the shooting, their teenage daughter Kim (Ellen Woglom), wakes up from a coma and begins remembering details about the night of the murder. The team learns that the girl was being stalked by a man named "Romeo." The investigation takes a scary turn when a hostage situation arises.