Brenda Joyce 
Dark Seduction 

He has sworn to protect the innocent through the ages… Malcolm is a newly chosen Master, a novice to his extraordinary — and dangerous — powers. When his lack of control results in a woman’s death he’s determined to fight his darkest desires, denying himself all pleasure…until fate sends him bookseller Claire.Yet nothing can prepare safety-conscious Claire for powerful medieval warrior Malcolm sweeping her back into his time. In this treacherous world Claire needs Malcolm to survive, but she must somehow keep him at arm’s length.For Malcolm’s soul is at stake — and fulfilling his desires could prove fatal…