Romance and Mystery are by far the two largest genres of fiction. Harlequin capitalized on this with their Intrigue series.
Romantic Suspense was first popularized in the 1950s and 1960s with the likes of Mary Stewart, Victoria Holt, and Phyllis Whitney. Harlequin launched Intrigue, with contemporary timelines and characters, in 1984.
The Intrigue series, like other "harlequin" series, developed subseries within, usually based on a family (The McKenna Legacy), an organization (The Colby Agency) or a location (The Rose Tattoo). The subseries could be written by a single author, as our example today where all 12 volumes in The Rose Tattoo subseries were written by Kelsey Roberts, or multi-author, like the Colby Agency subseries.
Her Mother's Arms combines an adopted heroine looking for her biological mother, a sexy ex-CIA agent, and someone looking to kill the heroine for the truths she may uncover. As with most serial romances the story unrolls quickly and ends predictably but it is a fun ride. Intrigues run to about 250 pages, still well within a single evening's sitting.
Her Mother's Arms is a typical example of the genre and the series. It gets a 4.0 rating on Goodreads. Her Mother's Arms is available on Biblio for as little as $3.97.
Me as a critic (be careful! the harshness will be well concealed!)