The mist / by Carla Neggers.

Enhanced descriptions from Syndetics:

When Lizzie Rush uncovers evidence that thrill-seeking billionaire Norman Estabrook may be at the center of an international criminal network, she finds herself playing a dangerous game of cat and mouse. Raised in the elite world of her hotelier family, educated in reality by her spy father, Lizzie is the perfect choice to slowly amass information that will take down Estabrook. But no good deed goes unpunished.

Despite Norman's arrest, Lizzie knows she's not safe. Estabrook will stop at nothing to exact revenge against the people who took him down--unless she stops him first. When she learns of a bomb that's about to go off in Boston, her instincts are proven right. But her warning doesn't come quickly enough. One detective is seriously injured in the blast and another, the FBI director's daughter, disappears. Then intelligence officer Will Davenport arrives with a single, simple message: Norman Estabrook is gone.

Lizzie doesn't know how Will found her or whose side he's on, but she does know he can help her prevent the killers from striking again. Now Lizzie--a woman who's spent the past year shrouded in a fog of deception--has no choice but to trust Will, a man who lives by a code of personal honor and answers to no one. At least until the mist clears and the frightening truth is revealed.