Frenchman's Creek by Daphne Du Maurier
The Restoration Court knows Lady Dona St Columb to be ripe for any folly, any outrage that will alter the tedium of her days. But there is another, secret Dona who longs for freedom, honest love - and sweetness, even if it is spiced with danger. To escape the shallowness of court life, Dona retreats to Navron, her husband's remote Cornish estate. There, she seeks peace in its solitary woods and hidden creeks. But she finds instead a daring pirate, hunted by all Cornwall, a Frenchman who, like Dona, would gamble his life for a moment's joy. Together, they embark upon a quest rife with danger and glory, one which bestows upon Dona the ultimate choice: sacrifice her lover to certain death or risk her own life to save him.