The Scandalous Vixen by Tracy Sumner

In this enemies-to-lovers Regency romance by award-winning author Tracy Sumner, a bold lady and a ruthless duke realize they need to agree to an ardent alliance to get what they want.

He knew at first sight.
She knew at first kiss.
Helena Astley, Lady Hell to the ton, has plans. To control her father’s shipping business, to live her way, by her rules. Her plan is going remarkably well until one ill-advised kiss invites the duke she doesn’t want but cannot resist into her life.

Hardnosed Roan Darlington, Duke of Leighton, cares little for society or finding a duchess. The only person ever to challenge him is the incorrigible, infuriating Helena Astley. The one woman he’s never been able to forget. When they’re caught in a ruinous situation, Roan offers her an alternative. A sham engagement she can break off after Christmas.
As they discover a world of forbidden pleasure, Helena must decide if she can relinquish a heart she vowed to withhold from the only man powerful enough to seize it.
And Roan must decide if falling madly, passionately in love is worth the risk.