When a devastating attack on the night of the State of the Union address claims the lives of the president and most of his Cabinet, the Housing and Urban Development secretary Tom Kirkman -- who was named the designated survivor in case of such an event -- finds himself promoted to leader of the free world. Suddenly thrust into his new position of power, Kirkman struggles to keep the country from dissolving into chaos and must adjust to his new normal, unaware of what fresh horrors may await the United States of America.
One year into office, President Thomas Kirkman juggles searching for the mastermind behind the attack on the Capitol Building, dealing with the day-to-day situations that take place at home and abroad, and helping a nation rebuild.
Agent Hannah Wells is an FBI agent who investigates the terrorist attack that killed President Richmond and every other person present at the State of the Union address, ever since Scott Wheeler, her love interest, was one of the casualties. Under Tom Kirkman's authority, she became the lead investigator into the conspiracy. During the events of the first season, Hannah was the one to eventually find that Peter MacLeish, the survivor of the Capitol bombing, was hiding in a bomb shelter beneath the Capitol and that he was involved with the conspirators responsible. She also uncovered many of the other conspirators, such as Catalan, also known as Nestor Lozano