Elizabeth Vargas

“20/20” explores one of the great United States government secrets of all time— how the administration and country will continue to operate in the wake of a catastrophic event that threatens the presidential line of succession. The special hour reports on real designated survivors, top secret bunkers and underground cities where the surviving government would be hidden, and how governments have reacted in the wake of devastating events including the day President Reagan was shot and the plane crash that took the lives of a Polish president and top Polish government officials. “The Real Designated Survivor” airs tonight on “20/20” Wednesday, November 23 (10:00 – 11:00 a.m., ET) on ABC.

Anchor Elizabeth Vargas speaks with former real-life designated survivors Dan Glickman (1997) and Gale Norton who was the designated survivor during the first State of the Union following the 9/11 attacks. They explain what it is like to be held in a separate, secure location and in the protection of the Secret Service during major events and how the role has changed post-9/11. In addition, Vargas sits down with award-winning actor Kiefer Sutherland who plays President Tom Kirkman on ABC’s “Designated Survivor." “20/20” goes behind the scenes on the set of “Designated Survivor” and talks to co-star and former White House staffer Kal Penn and series consultant Rich Klein about how they try to make the show as accurate as possible. "20/20" also investigates the 2010 Smolensk air disaster, which killed Polish President Lech Kaczyñski, top Polish government officials and military leaders, what caused the plane to go down and how the Polish government reacted to losing its leader.

ABC News Chief Global Affairs Correspondent Martha Raddatz gives a rare look at what happened the day John Hinckley Jr. attempted to assassinate former President Ronald Reagan. Raddatz speaks to former ABC News White House Correspondent Sam Donaldson who witnessed the attempted assassination and Reagan's National Security Advisor Richard Allen who plays never-before-televised audio recordings of the meetings that took place in the White House Situation Room that day, revealing top officials grappling with the continuity of government.

Also in the hour, Senior Justice Correspondent Pierre Thomas goes behind the fortified walls of a once-classified Congressional safe haven bunker and underground cities, built for U.S. government officials to assemble in the wake of a nuclear attack or other major disastrous event.

"20/20" is anchored by Elizabeth Vargas and David Muir. David Sloan is senior executive producer.