It's October 1962 and the White House has just received positive photographic evidence that the Soviets have moved nuclear missiles into Cuba and are preparing them as a threat to the U.S. mainland. As such, President John F. Kennedy (BRUCE GREENWOOD) has called a series of emergency meetings with his brother, Attorney General Bobby Kennedy (STEVEN CULP), and his most trusted aide, Special Assistant Kenneth P. O'Donnell (KEVIN COSTNER).
With time working against them as the Soviets covertly work to get the missiles - that could reach the U.S. in five minutes and kill more than 80 million people -- active, the three men meet with various White House and military officials who comprise the Executive Committee of the National Security Council, or ExComm for short.
Among them is Secretary of Defense Robert McNamara (DYLAN BAKER); Secretary of State Dean Rusk (HENRY STROZIER); Chairman of the Joint Chiefs of Staff, Gen. Maxwell Taylor (BILL SMITROVICH); Special Assistant for National Security Affairs McGeorge Bundy (FRANK WOOD); U.S. Ambassador to the United Nations, Adlai Stevenson (MICHAEL FAIRMAN); and advisors/counsel Ted Sorensen (TIM KELLEHER) and Dean Acheson (LEN CARIOU).
Soliciting advice from them as well as chief of staff of the United States Air Force, Gen. Curtis LeMay (KEVIN CONWAY), the three sort through their various options of how to deal with this new and unexpected threat. As the days pass and the tension increases as Soviet ships seem determined to break the naval blockage that Kennedy has ordered around Cuba, the President, his brother and Kenny do what they can to keep the situation from getting out of control while hoping that their choices don't cause a war to break out between the Soviet Union and the U.S.