Dangerous Secrets by Lisa Marie Rice

The Iceman never misses his target—until she becomes one.
The Iceman.
That’s what his Delta teammates call Nicholas Ireland. He’ll do whatever it takes to bring the bad guys down. Lie, kill, cheat, seduce. Now he’s on the trail of a psycho Russian mob boss who has gone to ground in a small, remote town in Vermont.
The quickest way to get to the mobster turns out to be by seducing the local librarian, Charity Prewitt. Not that it’s a chore.

She’s a real beauty.
But then the impossible happens.
Nick gets seduced right back.
Charity Prewitt lives a calm, low-key life, and that’s just how she likes it. Then her world is rocked by the sensual, charismatic man who storms into her life. She has no clue about Nick’s mission—the ruthless mobsters, the lethal schemes, and a nuclear bomb that must not fall into the wrong hands.