"The Beast Must Die" is a British television series that premiered in 2021. It is a thriller based on the 1954 novel by Nicholas Blake. The story follows a grieving mother, Frances Cairnes, who seeks revenge against the person she believes is responsible for her son's death. The series features a mix of suspense and drama, exploring themes of grief and justice. Jared Harris stars as the main character, while Billy Howle plays the suspected killer. The show combines elements of a whodunit with psychological tension, keeping viewers engaged throughout its episodes.