At the outset of this British murder mystery, a dispassionate narrator informs the audience that at least two of the characters seen onscreen will meet with sudden deaths. The story takes place in a rural British emergency hospital during the last years of WW2, when the "doodlebugs" (Nazi V-2 rockets) periodically interrupted the tranquility of the English countryside. When the local postman dies under anesthetic while undergoing a minor operation, six people are present, any one of whom could have murdered the patient. One of the nurses discovers that the man was indeed killed intentionally-just before she too is neatly dispatched by the mystery killer. Sent out from London to investigate is droll-but-businesslike Scotland Yard Inspector Cockrill (Alastair Sim, in one of his most memorable performances). He quickly ascertains that each of the five surviving witnesses had a motive for murder, and that it is likely that the killer will strike again if not immediately caught. After calmly prodding and probing about, Cockrill stages a phony operation, which the participants are led to believe is real. It is by this process that the murderer is revealed, leading to the now-classic denoument wherein a weary Cockrill submits his resignation from the Force-with the understanding that the resignation will be immediately destroyed upon receipt! Based on a novel by Christianna Brand, Green for Danger cried out for a subsequent series of Inspector Cockrill films, which alas never came to be.