The headless torso of a woman who disappeared in 1985, on the same day she filed domestic-abuse charges against her husband, is found by hikers in a wildlife preserve. The investigation quickly leads to the grisly discovery of 8 more decapitated bodies, the victims of a serial killer.

The 1978 murder of a young man is re-opened after the victim's mother finds a letter suggesting that his death wasn't random.

Lilly re-opens the 1929 case of a woman found dead in a ravine on Christmas Day when the victim's great-granddaughter comes in asking for help. Meanwhile, Lilly's estranged mother shows up, hoping to re-connect with her daughter.

The apparent 1958 suicide of a popular rock-and-roll DJ is reinvestigated after a documentary filmmaker discovers a tape recording made at the time of the victim's death by gunshot at his radio station. Also, Valens tries to get his brother to testify against a suspected pedophile.

Lilly investigates the deaths of a married couple who perished in 1981 when a supposedly accidental gas-leak explosion set their house on fire. The case is reopened when fragments of a bomb are discovered at the house during renovations. Back at headquarters, Stillman takes care of his 4-year-old grandson.

The team re-investigates their oldest cold case yet, the 1919 murder of a young woman who was a passionate advocate for women's right to vote.

The team re-opens the 2002 case of a 14-year-old math whiz whose half-brother exploited his unusual talents: card counting and safe cracking.

When the body of a newly missing boy is found in a cargo container along with the remains of three other victims who vanished in 1999-2003, the team realizes they're dealing with a serial killer.

The team re-opens the case of a woman who allegedly committed suicide in 1962 when the victim's granddaughter comes forth with evidence that the note found on the death scene -- then thought to be the suicide note -- was not written in the victim's handwriting.

Lilly and the team look into a 1989 case involving a Russian opera singer. Vera has a strong recollection of the case being a rookie in the department at the time.

The team re-opens the 1999 murder of a Cuban baseball star who fled to the U.S. after being fired from his team.

The 1991 murder of a 14-year-old girl in foster care who was a promising rapper is investigated. The probe reveals the victim lived in a gang-infested neighbourhood and was recently placed, along with her sister, with new foster parents.