Haven — John R. Maxim

Elizabeth Stride has come to Hilton Head Island to escape her past as "the Black Angel"--a ruthless assassin--and to escape Martin Kessler, a fellow operative who owned a piece of her soul. But just as she's begun to rebuild her shattered life, Kessler reappears, toppling Elizabeth's protective wall of anonymity.
A teenage girl about to be abducted from an exclusive nearby tennis club--a girl who unwittingly holds the key to horrific planned act of terrorism. By joining forces in a daring rescue of the girl, Elizabeth and Martin will be forced to put their fates in each other's hands one more time--and decide once and for all if they are to live together or apart. In doing so, they will be drawn into a secret war of fanaticism, greed, and doomsday technology.

And there will be no haven.