An Unforgettable Lady - J.R. Ward

Grace Hall is a society beauty-but her fortune has made her the target of a madman killing off Manhattan's most influential women. Her new live-in bodyguard is uncompromising, hard-hearted John Smith. Moving into Grace's penthouse is the last thing he wants, but saying no isn't an option. As he lays down the rules for his new client, angry sparks ignite between them-as does an incendiary desire. As the warm nights grow hot, and the killer closes in, Grace and Smith face a crucial choice: follow the rules or follow their hearts.