The story of The Danger Mark takes place around the Seagrave twins: Scott and Geraldine. Orphaned, but heirs to vast wealth, they're raised in near-total isolation. Well-educated, but terribly naive, their lives become vastly more interesting when they're released into formal society.
Geraldine is a heart-breaker and, thanks to the flattering attention of a hundred male admirers, learns about the fast-paced world of debutante balls, stolen kisses, dress-shopping and even (gasp) swearing. Still, her own heart belongs to one of the few childhood friends she was allowed: Duane Mallett, society rogue/talented artist. (Chambers himself was an artist, so generally, they're immediately identifiable as the "good guy".)
Duane and Geraldine do the predictable, farcical dance of the rom-com. They misunderstand one another, grow savagely jealous, burst into tears at a moment's notice and, generally speaking, seem to have a wonderful time.
But Geraldine has a secret...
Our lovely lady? She likes the likker. As a child, she used to steal cologne (?!) and flavored bon-bons. Now, as a grown lady, she occasionally sneaks off and drains entire flutes of champagne.
Geraldine's struggle with her affliction is the central theme to the book. She writes Duane daily about her battle with weakness - branding each letter sent from a "clean" day with a red cross (the titular mark). When she's satisfied with her self control, the two will be united in matrimony. Quite sweet as a thought, but painfully dull for reading, and mostly expressed as a series of increasingly-vapid letters between the two.
Fortunately, once you set aside Geraldine's drawn-out battle with the bottle, there's actually some fun buried in The Danger Mark. For one, her brother, Scott, is a blast. Not only did he fail to inherit the family trait of whininess, he has the adorably bad taste to fall in love with their governess (she's only a few years older than they are, it isn't really that dodgy). Scott is anxious to prove himself more than an idle society wastrel and throws himself into naturalism (not naturism - that'd be too awesome). To win his lady's hand, he's determined to write the definitive study of the Rose Beetle. So whilst his sister lounges around the house actively non-drinking his stock of formaldehyde, he's off mucking around on the estate, filling the bathtub with lizards.
Scott is, against all odds, a likeable character - a goofy academic surrounded by ornamental idiots. And the light of his eye, Kathleen, the one, rogue middle-class representative of the ensemble cast, is also pretty adorable. Unlike Geraldine's struggle with wine coolers, Kathleen has a real conflict. If she marries Scott, everyone will label her a gold-digger. But, against her own good will, she's falling more and more in love with him. (He's trying to name a beetle after her - which, in my mind, is about as romantic as it gets.)
Chambers has set the entire story against the background of financial melt-down. As the climax of the book approaches, the idle rich are suddenly forced to reacquaint themselves with the cruel, cruel cold world around them. In most cases, they sell their homes in the city and retire permanently to the countryside - although one particularly shattered family is compelled to move to Naples and live in a villa there. (My heart, it bleeds.) Scott and Duane, as a scientist and an artist, are personally unaffected. They'll miss their millions, but they're both committed to unworldly professions. Only the vulgar, really useless rich suffer.
With the exception of the core plot and the holier-than-though sermonizing tone (alas, sizable exceptions), The Danger Mark comes dangerously close to being an enjoyable read. The stultifying romantic dialogue is easily forgettable, but the looming financial apocalypse and the slightly offbeat second-tier characters both work to redeem it.
[Editor's note: The Danger Mark is available as a free ebook from Project Gutenberg. The Repairer of Reputations is our lengthy attempt to redeem the forgotten & derided works of Robert W. Chambers.]