It all starts when one afternoon he happens to meet his old public schoolmate Grexon Hay in Oxford Street. Hay is turned out like the proverbial dog's dinner but condescends to share Paul's supper of plump sausages. During their conversation over the bangers, Paul talks about his beloved, Sylvia Norman, whose father Aaron runs a second-hand book shop with a bit of pawnbroking on the side, or rather in the cellar. Alas, Paul and Sylvia cannot marry until he can support a wife and they have said nothing to her father for fear he will forbid Paul to visit.
Apparently Aaron Norman has "the manner of a frightened rabbit" and seems to be always looking over his shoulder with his one good eye. Obviously something fishy is going on there, but what?
Even stranger, when he sees the titular opal, diamond, and gold brooch, Aaron faints. Shown the brooch during their dinner, Hay makes an offer for it, but Paul refuses because it is his mother's and he prefers to pawn it so he can hopefully redeem it in due course.
We now meet the memorable Deborah Junk, servant of the Norman household and devoted to Sylvia. By far the most colourful person in the novel, her unique style of conversation would not disgrace a working class character created by Dickens, and when she is on-stage she dominates the scene.
But there's plenty going on when she's engaged elsewhere. Why did Aaron Norman faint when he saw the serpent brooch? Who is the man who warns Beecot against Hay, describing the latter as "a man on the market", and what does the curious phrase mean? Why did an Indian visitor to Aaron Norman's book emporium leave a pile of sugar on the counter? Does a truly ghastly guttersnipe born to hang know more than he lets on?
My verdict: The Opal Serpent contains some surprisingly strong content, such as certain comments made by the murderer, which would be disturbing even in this day and age, while the method used to kill the victim in full view of others is so awful I was surprised to find it in a novel of this vintage. Plus the use to which the brooch is put is equally grim.
This novel trots along at a steady pace with as many twists and turns as a serpent as it slithers its way to a rip-roaring denouement, and I must say the plot certainly underlines the traditional belief opals are unlucky! Recommended.