Her Wanton Wager (Mayhem in Mayfair)

A Wager She Can't Afford to Lose When her brother falls into the clutches of gamester Gavin Hunt, feisty heiress Persephone Fines will do whatever it takes to save him. Hunt offers her an outrageous proposition: he will release her brother ... if she can resist six nights of seduction. Can she withstand the scoundrel's wicked charm--and the shocking desire he rouses with each touch?
A Bet He's Determined to Win A product of London's violent stews, Gavin Hunt has clawed his way to success and power. Now he will stop at nothing to achieve his life-long goal: revenge upon the man who betrayed him. He plans to seduce his enemy's sister ... but doesn't count on losing his heart. Will he give up his need for vengeance--or risk forsaking the only woman he's ever loved?
From Six Nights ... to ForeverAs the battle of the sexes rages on and seduction flares into uncontrollable passion, Gavin and Percy must also fight a hidden enemy. Only by trusting one another can they defeat the threats of past and present. In this high-stakes game of love versus sin, what will be the outcome of ... Her Wanton Wager? 

Also in the Mayhem in Mayfair series: 
Her Husband's Harlot (Book 1) Her Wanton Wager (Book 2)Her Protector's Pleasure (Book 3)Her Prodigal Passion (Book 4--coming April 2014)

Also by this author: 
Abigail Jones (Chronicles of Abigail Jones - Book 1)