Credit: Former CIA director Michael Hayden has written a book called "Playing to the Edge." In it, he talks about some of the controversial activities in which he was involved.

The Hunt: Former CIA director looks back at counter-terrorism programs

‘Huge security gap’ lets dangerous packages enter US through postal system

The Hunt: US coalition, ISIL gear up for big battles ahead

The Hunt: US military says it’s wearing ISIL down

ISIL empire crumbling under relentless pressure

The Hunt: DC Police Chief discusses terror threats