The virgin and the rogue
(Book)

Series enumeration from fantasticfiction.com.

"Charlotte Langley has always been the prudent middle sister, so her family is not surprised when she makes the safe choice and agrees to wed her childhood sweetheart. But when she finds herself under the weather and drinks a 'healing' tonic, the potion provokes the most maddening desire ... for someone other than her betrothed. Kingston's rakehell ways are going to destroy him and he's vowed to change. His stepbrother's remote estate is just the place for a reformed rogue to hide. The last thing he wants is to be surrounded by society, but when he gets stuck alone with a wallflower who is already betrothed ... and she astonishes him with a fiery kiss, he forgets all about hiding. Although Charlotte appears meek, Kingston soon discovers there's a vixen inside, yearning to break free. Unable to forget their illicit moment of passion, Kingston vows to relive the encounter, but Charlotte has sworn it will never happen again--no matter how earth-shattering it was. But will a devilish rogue tempt her to risk everything for a chance at true love?"--Provided by publisher.