Joseph Petro served for 23 years as a special agent in the United States Secret Service; eleven of them with presidents and vice presidents. For four of those years he stood by the side of Ronald Reagan.

Following his career as a Navy Lieutenant, during which he patrolled the rivers and canals along the Vietnamese-Cambodian border, he worked his way up through the Secret Service to become one of the key men in charge of protecting the President. That journey through the Secret Service provides an individual look inside the most discreet law enforcement agency in the world, and a...