Detective Renée Ballard leads the LAPD's new and underfunded cold case division, tackling the city's long-forgotten crimes with empathy and determination. As she peels back layers of crimes spanning decades, including a serial killer's string of murders and a murdered John Doe, Renée soon uncovers a dangerous conspiracy within the department. With the help of her volunteer team and retired detective Harry Bosch, Detective Ballard navigates personal trauma, professional challenges, and life-threatening dangers to expose the truth.