Simply "X"

Greyson Daniels' life is quite predictable. Although he is handsome, successful, and a genuinely good man, he's fairly boring. Twice monthly, he travels to New York on business, and it's there that a secret admirer completely upends his world, forcing him out of his shell. Playing her game, and following her clues, he believes that he has finally discovered who she is..... What he finds is that he couldn't have been more wrong.