Set in Regency-era England (early 19th century) - the young son of a wealthy couple is kidnapped, to be ransomed by the return of a ring, a family heirloom the kidnapper believes the couple has possession of. As they seek to track down the ring's whereabouts, the secrets each has kept from the other come to light, threatening to destroy their idyllic existence and the perfect marriage everyone believed they had - including themselves.
A few too many easy fixes/coincidences for me (like, hey, we just happen to have an aunt who lives in the city where we need to find someone! and despite her social status, she just happens
to be a bit of a rogue and runs in the type of somewhat-shady circle where people might know the person being sought!), but I liked the focus on how betrayal - both real and assumed - tests the bonds of even people who love each other. After a while I got a little tired of the scenes of emotional turmoil (especially since - seriously? you knew from the start that these people would end up recognizing that, despite it all, they did still love each other), but it was truly a different twist on this kind of mystery/romance, and the background on post-French Revolution/Napoleonic era politics was interesting as well.