A recently released prisoner lives alone in his cabin so that his bad temper won't get him back in any more trouble, but his peaceful existence is disrupted when a mysterious woman arrives.

Chinese sleuth Charlie Chan discovers a scheme for the theft of government radar plans while investigating several murders.

Charlie Chan is an agent of the US government working in Washington DC and he is assigned to investigate the murder of the inventor of a highly advanced torpedo. Aiding Chan is his overeager but dull-witted son Tommy and his daughter Iris.