Wyndcross by Martha Keyes

When Kate Matcham's choices are tainted by scandal and secrets, she faces a dilemma: become a scoundrel's mistress or enter into a marriage of convenience—little does she know, her heart has other plans. With a dubious inheritance hanging in the balance, Kate Matcham is confronted with two offers: one, to become the mistress of a notorious scoundrel, and the other, a marriage of convenience. Reluctant to choose, she embarks on a final adventure—a visit to a childhood friend. However, what should have been a last hurrah takes an unexpected turn when Kate finds herself falling for the very man her friend intends to marry, a gentleman of higher station harboring enigmatic secrets. As smuggling operations grip the county, shrouding everyone in deceit, Kate's options dwindle. Torn between her deepening affection for a man of duplicity, her loyalty to her friend, and a long-standing promise to avenge her father's murder, Kate's path to destiny is fraught with peril and passion. Wyndcross is a clean, full-length Regency romance with a twist of intrigue and all the things readers love most about the Regency Era