'The English should confine their murders to their own country' is the view held by Parisians when Lady Dorothy Strathy, sister of the Earl of Tain, is discovered stabbed in her hotel room. This opinion is held by none more strongly than Courtrand, the head of the Sûreté, an outrageous snob who regards the case as closed when it is discovered that Lady Strathy's paid companion, Miss Newbolt, was the first on the scene.

However, Inspector Gautier is not so easily swayed and comes up with a number of awkward clues which throw doubt on Courtrand's theory, facing in the process the shady underworld of male prostitution and back-street throat-cutting - alongside more personal troubles including the death of his ex-wife - in a case with a startling dénouement.