Silver Fire by Victoria Paige

Sophie Marie Leroux is a genius physicist who has developed the technology that can be used as a limitless power source. It is also rumored that she is in possession of plans that can cause widespread destruction. Certain factions want to see that research buried, and the only way to make it happen is to get rid of Sophie.
Derek Lockwood has avoided commitment all his life. His past involvements in high-risk missions are not exactly building blocks for meaningful relationships. Now an executive for a defense company, he finds himself attracted to his new business partner.

When mounting threats endanger the woman he would forsake for all others, Derek steps in as her protector.
However, behind Sophie’s brilliant mind lurks a dark past, and Derek will need all his intellectual and sensual expertise to break through her emotional minefield.

* Can be read as standalone. Mature audience only.