His Scandalous Duchess — Sara Blayne

SHE WOULD BE HIS MISTRESS...
Irrepressible Althea Wintergreen sacrifices her own reputation to save her sister's by claiming to be the mother of her illegitimate niece. Shrouded in scandal, she has no illusions about the amorous intentions of the wholly disreputable and devastatingly handsome Lucius Keene, the Duke of Traherne. Tempted by the sweet promise of passion in Lucius' kiss and her own secret desire to know love, Althea aids him wholeheartedly in her own seduction!

...BUT NOT HIS WIFE!
Though Lucius Keene is a confirmed rake and dedicated bachelor, he is above all a gentleman. Determined to set matters right, he proposes marriage to the unconventional, delightful Althea, never anticipating London's most eligible Duke would be turned down flat! Aware his own heart is becoming dangerously involved in the matter, especially as sinister doings are afoot, he vows to convince noble Althea that her "scandalous" past is no reason to deny them both a future of bliss in each other's arms...