At a meeting of Quenborough Borough Council, the Mayor, Sir John Assington, is accused by Alderman Trant of wasting money and turning a blind eye to speculators on the make.
Then Trant is stabbed with his own knife, and while dying, manages to scratch the initials ‘MA’ on a piece of paper.
Local Chief Constable Race is on the case. He is new to the force, so Superintendent Vorley comes to his aid. With the help of Scotland Yard, in the shape of Inspector Lott, they each bring a different approach to the investigation.