National Treasure: The Survivalist, Book 10 (Unabridged‪)‬

National Treasure is the tenth book in Dr. Bradley's Survivalist series. 

Just when it looks like Deputy Marshal Mason Raines might finally settle into a life free from violence, he receives an emergency distress call from the New Colony. Not only has his handler been brutally attacked, but the life of a treacherous woman he once loved is also in danger. Forced to choose between contentment and duty, he must once again forsake his own happiness for the welfare of others. This time, however, he would be well-served to remember that the motives of those being rescued are anything but pure.

Faced with an equally daunting challenge, Tanner and Samantha travel west to Fort Knox, Kentucky. Their goal is as simple as it is impossible: to rob the nation's gold vault of all its remaining treasure. The trip takes an unexpected turn, and they find themselves recruited by an old woman eager to lay her husband to rest. But even that task is not without moral choices that have them questioning what it means to be one of the nation's last remaining survivors.