Order to Kill, by Kyle Mills

Kyle Mills continues to raise the bar and get Vince Flynn's Mitch Rapp into bigger messes.  Order to Kill brings Rapp against perhaps his toughest opponent yet, and puts him undercover in the toughest place yet.

To the chagrin of the Americans, the Pakistanis are playing fast and loose with the security of their nuclear weapons.  On a mission to recover one, Mitch and his team fall into a trap.  Rapp's colleague Scott Coleman nearly gets taken out by a fighter whose prowess makes even Coleman and Rapp pause. 

This super fighter turns out to be Russian, and the nukes turn out to be duds, so Rapp has to figure out who has the actual nuclear material and what the Russians have to do with it.  Of course the Russians want to detonate dirty bombs in Saudi oil fields and make it look like ISIS did it.  Rapp embeds himself in ISIS, impersonating an American ISIS member.  If you've read a Mitch Rapp novel, you know it's no spoiler to tell you Rapp prevails.

Order to Kill has the great action and intricate plotting that characterizes the entire Mitch Rapp series.  Mills has fully taken the mantle of Flynn, may he rest in peace.