Much of the novel takes place in Northern Ireland, particularly around Belfast, where Crofts had spent a great deal of his younger years before moving to England.

Crofts' admiration for the Royal Ulster Constabulary, and implicitly the Northern Irish state, is clear throughout the novel although it features little direct reference to politics.

[2] When Sir John Magill, an Irish linen millionaire, disappears on a rare visit to Belfast, the assistance of Scotland Yard is sought.

Inspector French is assigned to the case and travels to Ireland where he collaborates with the local police force to follow up on various clues, concluding in the discovery of Sir John's body in a shallow grave on the edge of Major Magill's country estate outside Belfast.

The evidence appears to point to Major Magill's having committed the murder in order to come into a large inheritance from his father, which he needed due to the struggling financial situation of the linen industry.