A newcomer to a remote village is murdered, plunging the community into a web of secrets that challenges the sanity of the investigating detective. Detective-Inspector Young is baffled by the impossible nature of the crime, suspecting forces beyond his comprehension. He enlists the help of Desmond Merrion, a brilliant amateur sleuth, to unravel the mystery. As Merrion becomes entangled with a local woman, Mavis Owerton, he must determine if she is a key to the village's hidden truths or a part of the deception.

The premise sets up a classic Golden Age mystery with a focus on intricate plotting and intellectual deduction. The introduction of an amateur sleuth alongside a police detective suggests a dynamic partnership, common in the genre, where contrasting methods are employed to solve the crime. The isolated village setting and the 'impossible' nature of the murder point towards a puzzle box narrative, likely involving a closed circle of suspects and hidden motives. The romantic subplot with Mavis Owerton hints at potential misdirection or a deeper connection to the central mystery, adding layers of personal stakes to the investigation.