The seventh season opens 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.

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.