At a lonely wartime hospital, the local postman, injured in a flying bomb explosion dies unexpectedly during surgery.This isolated incident leads to the chief surgeon,his team of doctors and nurses, becoming suspects in a series of suspicious deaths. When Inspector Cockrill (Alastair Sim) starts investigating, he finds four poison pills missing.... Good performances from Trevor Howard, Leo Genn, and Rosamund John, but the film is stolen by the wonderful Alastair Sim.