Gregg Kaplan is not an ordinary man, but a man with special skills, courtesy of the United States Government. His assignment is to stay off the grid when he innocently stumbles into a blown witness protection detail in Little Rock, Arkansas. He simply could not walk away from the impending mayhem. After the dust settles, a mortally wounded Deputy U.S. Marshal makes him promise to personally deliver the witness to a U.S. Marshals Service safe site. Not just a promise, an oath.

Terrorism, duty, and personal safety collide when Jake Pendleton, an investigator for the NTSB, is called to investigate an aircraft accident in Savannah, Georgia during the St. Patrick's Day celebration. The accident, which at first appears to be quite run-of-the-mill, turns out to be anything but. Since Jake is not willing to pretend there are no suspicious circumstances and more than the usual share of rather unlikely "coincidences," he sets off a veritable avalanche of secrets, violence and treachery.

When elite Navy Seal Troy Stark is forced into retirement for his dubious respect for authority, he dreads the quiet life awaiting him with his brothers and buddies in Yonkers, New York. But the quiet doesn’t last long: The NYPD needs Troy’s military expertise to help find and stop a major terrorist threat to New York City. To pre-empt the attack, they need him to fly to Europe and stop it at its source—using any means necessary.

Court Gentry is known as The Gray Man—a legend in the covert realm, moving silently from job to job, accomplishing the impossible, and then fading away. And he always hits his target. But there are forces more lethal than Gentry in the world. And in their eyes, Gentry has just outlived his usefulness. Now, he is going to prove that for him, there's no gray area between killing for a living-and killing to stay alive.

Tom Walker arrives in his hometown, and in less than an hour, the clandestine government program he works for tries to kill him. Not much of a welcome. To make matters worse, the farm where he seeks refuge has–unbeknownst to the owner, Leila–an underground drug ring operating on property. And despite this newfound danger, Leila risks her own life just to nurse Walker back to health.