Her Tempestuous Duke by Elizabeth Keysian

She can no more tame him than she can the storm.
She knows there’s good in him somewhere. At least, she hopes there is…

Saved from drowning by a man as tempestuous as the midwinter storm that sank her boat, Miss Minerva Harte’s future looks grim. Her rescuer, Parys Pendorran, lives like a hermit in a ruined castle, tormented by secrets and embittered by the past. Despite her fear of him, Minerva is fascinated by this sinfully attractive stranger. Surely such a man, despite his scars, is worth saving?

Parys wants Minerva to leave, but when her guardian and the wrecked boat’s other occupants struggle ashore, he casts them into his dungeon. The sight of Minerva’s protector, Lord Anthony, turns Parys into what local legend says he is; a terrifying warlock surrounded by ghosts and watched over by a monstrous hound. In a single night, the sea has given Parys both a tempting young beauty, and the man he has vowed to destroy.