Valens partners with Rush to locate her abducted, drug-addicted sister, while Jeffries tries to bring justice to the case of a murdered teenaged girl that has haunted him for 17 years.
Rush tries to ignore her father's appeals to give her troublemaker sister another chance after she suddenly resurfaces.
Rush and FBI agent Ryan Cavanaugh discover their attraction for one another while investigating the 1969 murder of a GI at Woodstock, and Vera helps his married ex-girlfriend, Megan, after sentimental jewelry is stolen from her home.
After determining the serial killer's identity - and some of his likely future targets - the team and the FBI work together to apprehend him while trying to locate and protect the people he's preparing to kill.
When ballistics tie a recent murder case of Rush's to a serial killer who was seemingly inactive for 27 years, a tough FBI agent with ties to Stillman shows up to enlist the team's aid in finding the killer who has eluded her for 30 years.
Realizing that the missing Vera has finally hit rock bottom, his worried team members hope that a new twist to a 2006 arson case, which he was secretly obsessing about in recent weeks, might supply leads to his whereabouts.
The 1986 murder of a dock worker who moonlighted as a wrestler is investigated. Meanwhile, Valens follows a lead that could result in the capture of his mother's rapist.
Lilly and the team attend a colleague's wedding and are persuaded by Jeffries to investigate whether the bride killed her former fiancé two years earlier - just hours after he called off their nuptials.
The 1971 death of a teen aerialist who fell during a dangerous circus performance is investigated. New evidence suggests her fall wasn't an accident.
The 1983 murder of a graffiti artist who died after spray paint was forced down his throat is investigated. Meanwhile, new details emerge about the person who mugged Valen's mother; and Lilly faces additional legal hurdles thrown her way by Moe.
The 1974 murder of a private investigator is probed after his body is discovered in the cement foundation of a demolished building. The investigation reveals the victim uncovered damaging information about his last few clients and that he hired a tough associate to provide muscle during his final investigation.
The 2005 murder of an Army recruiter who was killed just two days before his scheduled deployment to Iraq is reinvestigated after a soldier comes forward with new evidence.
The 1980 murder of a minor-league hockey player is investigated. The victim was killed on his team's home rink the night the U.S. hockey team defeated the Soviet Union in the Olympic Games.
The 1999 death of a high-school debate champion, which was originally ruled a suicide, is investigated after new evidence suggests he was murdered. The probe reveals the victim received a scholarship at a top private school and died shortly after losing a debate at the competitive campus.
The 1983 murder of a Chinese-American teen is reinvestigated. The case was originally handled by Stillman. The probe reveals the victim's girlfriend was killed by Chinese gang members three months earlier at a festival and that the dead man may have been seeking revenge.
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.
The 1986 murder of a jockey is investigated after his body is discovered in a mass grave for horses. The victim disappeared shortly after losing a race that he had planned to be his finale before retiring.
The 1944 murder of a female pilot who flew noncombat missions for the U.S. during World War II is investigated. The victim was part of a civilian program that assisted the Army and Air Force. Meanwhile, the man who ran Lilly's car off a road is released from prison on bail.
The 1970 murder of a musician who was instrumental in creating the Philadelphia soul sound is reinvestigated. The victim tried to keep his involvement in the music scene from his strict minister father. Meanwhile, Lilly meets her teen stepbrother, Finn.
The 2004 murder of a teen at a juvenile detention center is investigated. The boy was wrongly sent to the facility and was killed before Valens could get him released. Meanwhile, Lilly reconnects with former flame Eddie Saccardo, a narcotics officer.
The team re-opens the 1995 case of a skateboarding prodigy who lived on the streets.
With the team investigating the 1966 shipboard murder of a young woman traveling in steerage on a luxury ocean liner who was believed to have committed suicide by jumping overboard. But new evidence indicates otherwise. Meanwhile, the trial of a military academy official who attempted to harm Lilly begins.
