A man is good for only one thing.

Dr. Marietta Dalrymple wants a baby, but all she wants from a man is his sperm. A professor of evolutionary biology, Marietta can explain away romantic love with scholarly theories of why men and women are compelled to copulate. Monogamy, she believes, is a state most males can't achieve.

So what is Marietta to do after she mistakes Cash "Jax" Jackson for the carefully screened sperm donor she hired to impregnate her? Especially when Jax doesn't know anything about the legal document the other man signed relinquishing all rights to the child.

Jax soon sets his sights on more than Marietta's unborn baby. But can he prove to her that romantic love truly does exist? Or will the secret he's keeping destroy any chance these unlikely lovers have at happiness?