Former military intelligence officer, Clayton Devereux, resigned his commission in 1930 and set-up his own detective agency, which he runs with his secretary Rose and the occasional hiring of his street-wise cohort Ollie Jones.

Their routine work of divorce and petty crime usually bores the urbane Devereux so he is intrigued, and keen to help, when a former colleague asks him to assist unofficially in the search for an M.I.5 operative who has gone missing.

In a plot that is woven against the actual political and social tensions of the period, the story twists and turns as Devereux’s clandestine investigation gradually uncovers a dangerous and sinister threat to national security and the stability of the country.

Solving the case and finally defeating the forces set against him costs Devereux far more than he was prepared to lose.