From the pages of a spy novel......

"How a crippling intelligence loss led the CIA on a mole hunt" PBS NewsHour 1/18/2018

Excerpt

SUMMARY:  Jerry Chun Shing Lee, a former CIA officer, was arrested this week on charges of mishandling classified information.  A massive Mole Hunt inside the agency has been on for years for the person who may have helped the Chinese government roll up a significant piece of the U.S. spying network in that country.  John Yang learns more from Adam Goldman of The New York Times.