Devilish

Devilish by Beverley, Jo. mass_market edition. ISBN: 9780451217943.

The Marquess of Rothgar has been haunted all his life by witnessing his mother turn mad and murder his baby sister. With such blood in his veins, he is resolved not to marry, but then he meets Lady Arradale. Diana, Countess of Arradale is that rarest of creatures, a peeress in her own right, holding extraordinary power and influence for a woman. To marry risks losing her independence, and yet when she meets the Marquess of Rothgar, for the first time she is tempted. She is tempted in a strictly physical way as well, and surely that might be safe when he is the one man in England who does not want to marry her wealth and power. Both decide it would be wiser to part, but then the king, alarmed by awareness of such a powerful woman loose in his realm, commands Rothgar to escort the countess to London. A RITA award winning book.