A new Smithsonian Channel special will reveal one of the greatest secrets of the Vietnam War. THE SPY IN THE HANOI HILTON, premiering Monday, April 27 at 8 p.m. ET/PT, uncovers the true story of POWs inside the Hỏa Lò Prison, known as the Hanoi Hilton, who created a high-level espionage operation that reached all the way to the CIA and the White House. This included sending radio transmissions to the Pentagon and President Nixon’s White House during the brutal Christmas Bombings of 1972, signaling that POWs inside the Hanoi Hilton were still alive and that the raid should continue.