捕快瑞特只身破获了一起劫机案，谁知被他击毙的一位劫匪却恰是某国国王的弟弟 ，为避免两国关系紧张，瑞特被迫进狱。与此同时，其他劫匪却很快逃狱逃脱，狡计占领印斯摩斯牢狱，以敲诈当地当局。瑞特刚被押往印斯摩斯，便发明牢狱已遭到劫匪掌握，因此应机立中断，一面批示其它狱友与劫匪周旋，一面与警局联络申报真实情况，此次，漏网的劫匪悉…

Childhood friends Tommy and Tuppence meet in London after having served in World War I. Recently demobed, short of money, and with no job prospects, they decide to become adventurers for hire. Soon, they are employed by the British Government to locate a secret treaty signed before the war.