The Witness by Nora Roberts

Daughter of a controlling mother, Elizabeth finally let loose one night, drinking at a nightclub and letting a strange man's seductive Russian accent lure her to a house far away. The events that followed changed her life forever.

Twelve years later, the woman known as Abigail Lowery lives on the outskirts of a small town in the Ozarks. A freelance programmer, she designs sophisticated security systems - and supplements her own security with a fierce dog and an assortment of firearms. She keeps to herself, saying little, revealing nothing. But Abigail's reserve only intrigues police chief Brooks Gleason. Her logical mind, her secretive nature, her unromantic viewpoints leave him fascinated but frustrated. He suspects that Abigail needs protection from something - and that her elaborate defenses hide a story that needs to be revealed.