Charismatic detective Alex Ridley retires from the police force after years of loyal service. Ridley's replacement is acting DI Carol Farman, his former protégée who was mentored by Ridley for many years. Carol works on a complex and compelling murder case that suddenly takes a dark and unexpected turn. She turns to her old mentor for support, eager to access Ridley's unique insight into crime solving, which has served them so well in the past.