"The Beast Must Die" is a suspenseful British thriller, available as both a novel and a television series, centered on a mother's revenge after her son is fatally hit by a speeding car. Frances Cairns, driven by grief and the police's lack of progress, decides to take matters into her own hands, posing as a novelist to ingratiate herself with the family of the man she believes is responsible. Detective Nigel Strangeways, also dealing with his own grief and a potentially linked police cover-up, finds himself entangled in Frances's plan and the investigation into the hit-and-run.