Excavating the CIA Archives

This April 13, 2016, file photo shows the seal of the Central Intelligence Agency at CIA headquarters in Langley, Va.

John Prados, expert on American intelligence history, senior fellow of the National Security Archive in Washington, D.C. and author of The Ghosts of Langley: Into the CIA's Heart of Darkness (The New Press, 2017), discusses what he learned from excavating the C.I.A. archives.