Tarquin and the Daring Duchess - Tarquin the Ravisher Regency Series, #4

TARQUIN THE RAVISHERA nod from him can ruin a reputation.Ladies swoon at the mere mention of his name... Tarquin is the young nobleman whom every jealous husband and vengeful father wants to kill. No woman is safe from this master of seduction-from blushing debutantes to comely society matrons, spoiled princesses to starchy governesses, stern chaperones to flighty duchesses. What Tarquin desires, he takes-and he never leaves a lady wanting. An assassination plot is afoot, and the protectors of king and country must work fast to discover the malefactors.
Tarquin finds help from very unusual quarters-Lady Caroline, bubbly little wife of the abominable Duke of Percy. The duchess has a few aces up her sleeve, both of the political and the deliciously decadent kind, as Tarquin discovers with ecstatic delight.