Lie down in roses / Heather Graham.

Originally published in 1988 under the name of Shannon Drake.

The willful and beautiful Lady Genevieve would do anything to save her beloved Edenby Castle The willful and beautiful Lady Genevieve would do anything to save her beloved Edenby Castle even if she had to share the name--and bed--of her most treacherous foe. He was Lord Tristan, nobleman and knight. Magnificent in battle, he would lead his invading army across the land, only to become captive to the sensual charms of the bold enchantress who was secretly plotting his destruction. They were born to be enemies and destined to be lovers--players in a perilous game of intrigue and passion where the price was one woman's innocence . . . and the prize was one man's heart.