One moment, New Jersey state trooper Mike Russell was working undercover, playing the role of an up-and-coming mobster hoping to infiltrate a Mafia family crew. The next, he was lying facedown in an alley after being ambushed and shot in the back of the head by a mobster over a dispute.

Russell miraculously healed, and rather than press charges, he maintained his cover. Soon he had a stroke of good luck when he saved a man from an attack by two street thugs. The man he saved turned out to be Andy Gerardo, one of the ranking captains of the Genovese crime family. Quickly earning the...