The Duke's Challenge (Duke #4)
Fenella J. Miller

Major Jack Griffin, a disfigured and dissolute Napoleonic war veteran, now holds the title and is determined not to allow Charlotte and her family to remain at Thurston. He offers her an impossible challenge. Charlotte and the children can remain if she can improve the dilapidated house and poor estate withing two months. She has no choice but to accept.
Despite his many faults Charlotte is drawn to Jack. As their love grows there are sinister forces working to ruin their plans. Can they unmask the murderous plotters before they lose everything?