Wild At Heart.
(Book)

They called him the "lost man." Raised in the woods, without speech, without civilization, he was beautifully, wonderfully wild. And when he was captured and locked away to be studied by scientists, he was treated more like an animal than a human being. Only Sydney, daughter of a renowned anthropologist, looked beyond the wildness to see the man. Something in his fierce loneliness called to her, imploring her to help him, to save him, to make him her best friend. But the world was not nearly so understandning. And soon, still haunted by the mysterious tragedy of his past, he wanted more than friendship. He wanted all of her--her love, her heart, and her soul....