One night to be sinful - Samantha Garver

A fine and true friend, Calvin Garrett never anticipated what he would undertake in the name of loyalty to Lord Wolcott. Posing as a butler, he appears at the door of Wolcott's fiercely independent sister, Abigail, charged with uncovering the strange and sinister happenings at her country home. Certainly, he hoped playing servant to an unconventional woman would be a short-lived task. But when he meets his stunning new mistress, the scheme he had in mind takes a turn for the tempting...

Abigail has never encountered a butler so...magnetic. However, he comes
highly recommended and she is desperate for help. The troubles and danger
plaguing her estate are enough to make a sane woman cling to strong
shoulders, but her awareness of her new employee has much more to do with a
longing from deep within her heart. Clearly, she has bigger problems than a
dizzying attraction to a male. Soon, though, sleepless nights filled with
danger and desire form a volatile mix that promises to turn Abigail from a
confirmed spinster into a woman ready for love...