An explosion at the National Assembly kills everyone in the cabinet, leaving Park Mu-jin, the Minister of Environment, to become the next president. Park Mu-jin is a scientist-turned-politician who has no ambitions in politics, but as the acting president for 60 days, he is compelled to investigate the truth behind the attack. Based on the popular American series, Designated Survivor.

As a chief of staff in the National Assembly, Jang Tae-jun influences power behind the scenes while pursuing his own ambitions to rise to the top.