Green for Danger

Green for Danger is a popular 1944 detective novel by British writer Christianna Brand, praised for its clever plot, interesting characters, and wartime hospital setting. It was made into a 1946 film which is regarded by film historians as one of the greatest screen adaptations of a Golden Age mystery novel. (The 2016 BBC Father Brown episode 'The Rod of Asclepius' is also effectively an adaptation of the novel).

Plot summary
A murder takes place in a rural British hospital. Inspector Cockrill is tasked to determine whodunit when the head nurse is killed after revealing that the death of a patient under anaesthesia was no accident. Cockrill states at one point, "My presence lay over the hospital like a pall - I found it all tremendously enjoyable." After another murder attempt leaves a nurse dangerously ill he re-stages the operation in order to unmask the murderer.