[1] It is the twenty-first in his series of novels featuring Chief Inspector French of Scotland Yard, written during the Golden Age of Detective Fiction.

It was one of a number of novels by Crofts during the period which portray overly acquisitive businessman in a bad light[2] and constitutes an attack on patent medicines.

[3] James Tarrant, a ruthlessly ambitious young man working as an assistant in a chemist shop, hatches a radical plan.

To raise funds for his venture Tarrant seduces Merle, an attractive nurse, and promises marriage once their business is a success.

Shortly after announcing his engagement, he is discovered dead from drowning on a fishing trip, having ingested a large amount of poison.