The Beast Must Die is a 1938 detective novel by Cecil Day-Lewis, written under the pen name of Nicholas Blake.

After his young son is run down and killed by a speeding car in the Gloucestershire village where he lives, mystery novelist Frank Cairnes is angry when the police fail to trace the culprit.

Deciding to investigate on his own, he finds out by chance that the passenger in the car is a rising film actress, Lena Lawson.

Pretending to be writing a new novel set in a film studio, he meets Lena in London posing under his pen name Felix Lane.

Knowing that he will be the prime suspect, Cairnes calls in the private detective Nigel Strangeways to clear him of the murder.