My Wicked Marquess (The Inferno Club)

is book #1 of The Inferno Club by Gaelen Foley.
==Book Description==
To restore family honor the Marquess of Rotherstone faces his most dangerous mission—finding the perfect bride . . . — To London's aristocracy, the Inferno Club is a scandalous society of men no proper young lady would acknowledge. But though they are publicly notorious for pursuing all manner of debauchery, in private they are warriors who would do anything to protect king and country.
The Marquess of Rotherstone has decided it's time to restore the family's good name. But as a member of the Inferno Club, he knows there is only one way to redeem himself in Society's eyes: marry a lady of impeccable beauty and breeding, whose reputation is, above all, spotless.
Someone quite unlike Daphne Starling. True, she's temptingly lovely, but a jilted suitor has nearly ruined her reputation. Still, Max cannot resist her allure—or the challenge of proving London's gossips wrong. He would do anything to win her hand . . . and show that even a wicked marquess can make a perfect husband. 
(Description from paperbackswap.com)