Mirabelle Leicester has always known that her husband Leon Gonsalez is the 'possessor of innumerable coats of arms, quarterings, family mottoes direct and affiliated' (in the words of Edgar Wallace), but since their marriage she has discovered that he also has a real family, including a revolutionary cousin from Barcelona and an aristocratic aunt. When the cousin asks for Leon's and Mirabelle's assistance in clearing his name, the investigation takes them to Spain: trailing kidnappers, dodging gunmen and encountering old friends.