The Forbidden Duke (The Untouchables)

Spinster Miss Eleanor Lockhart is suddenly homeless and employment is her only option. Ruined after succumbing to a scoundrel's excessive charm nearly a decade ago, she's lucky to obtain a position as a paid companion and committed to behaving with the utmost propriety. She definitely shouldn't be in the arms of a man capable of utterly destroying what little remains of her reputation...

Titus St. John, Duke of Kendal, is known as the Forbidden Duke, a mysterious, intimidating figure who enters Society just once each year at his stepmother's ball. A decade ago, he was a devil-may-care rake until his idle roguery brought about the ruin of Eleanor Lockhart--and his resulting self-imposed isolation. Now she's back, and she needs his help. But by "saving" her, he may just ruin her life all over again.