Enemy at the Gates (Mitch Rapp 20) by Vince Flynn

THE NEW PULSE-POUNDING THRILLER IN THE NEW YORK TIMES BESTSELLING MITCH RAPP SERIES
When a high-level mole with power to rewrite world order infiltrates the CIA, Rapp must uncover a threat like no other.
After a blackout swept the nation, America is resuming life as normal with a new president, one unlike any Mitch Rapp has worked with in the past. As Rapp backs away, the new president, in turn, questions his loyalty.
Rapp decides to take a much-needed break. But when it’s discovered that a mole in the CIA has been digging into their systems for information on Nicholas Ward, the world’s first trillionaire and the man personally overseeing cutting-edge medical research in Uganda, he is pulled back onto the job.
Protecting Ward, Rapp is completely cut off from the agency as he works to identify and expose the mole. But the situation is complex. And the threat is one he could never have imagined…