Some interesting moments and characters but melodramatic, a plot too dependent upon coincidence, and loaded with propaganda in a defense of Britain in WW I. Un-needed propaganda one would think, for it was published in 1920.
Oppenheim has, among other irritating quirks, a tendency to tease by offering the beginning of clues, only to withdraw or interrupt them as an artificial means of maintaining mystery. Despite that, chances are you'll identify the murderer before he confesses.
What's more, neither hero or heroine respopnd realistically to motivation.
Those of us who've read much of Len Deighton and John LeCarre, not to mention true narratives of espionage, can only gape at the extremely weak security procedures described in this novel. In addition, the mole (or a choice between two moles) is apparent early on, and narrows down well before the end.
Yes, the characters are decent and the setting pleasing, but realism is mighty sparse.
I'm becoming quite put out with Oppenheim. This story makes a promising start, having a deeply-flawed but sympathetic hero, and an attractive if unbelievably angelic heroine.
Goes downhill as the hero begins to make it a habit to blab about his crime at the drop of a hat, while showing a naive conviction in his own safety from the law. Not to worry, however, as he manages to bring out the mother instinct in all women, and they'll protect him. More than that, his enemy turns into a forgiving Christian gentleman for almost no reason at all.