Retired archaeologist Judith Potts's peaceful evening in Marlow is shattered when she hears a gunshot coming from her neighbor's garden.

Despite Tanika's warnings to stay away from the case, the trio follow a trail of clues left by the murder weapon, uncovering new evidence that leads them to a chilling discovery - they have a serial killer on their hands!

As the police race against time, Tanika recruits the trio as civilian advisors to help catch the killer. The police make a forensic breakthrough on the crime scene evidence, have they caught their killer?