In February 1925 the Great War is still raging on the Western Front, but in Westminster, at the centre of Hardcastle’s bailiwick, a policeman is shot dead.

At first, Hardcastle believes the murderer to have been a disturbed burglar.   But then, two days later, there is another killing – Isabel Plowman, the beautiful wife of a Royal Flying Corps Officer, on whose doorstep the first victim was killed.

As enquiries continue, attention focuses on an antiquarian bookseller, a struggling artist, a reporter, officers of the Royal Flying Corps, both in England and in France…and Hardcastle must uncover a tangle of lies, emotions and betrayals before he can get to the truth.