"The Beast Must Die" is a crime novel written by British author Nicholas Blake, published in 1939. The story follows a wealthy man named Frank Cairns, who seeks revenge after his son is killed in a hit-and-run accident. Determined to find the driver, he devises a plan to lure the culprit into a trap. The novel is notable for its exploration of themes such as justice and morality. It is also recognized for its clever plot twists and engaging narrative style, making it a significant work in the genre of detective fiction.