Designated Survivor
Tom Kirkman is a somewhat reluctant politician in being appointed by US President Richmond to be a low level member of his Cabinet, the appointment due to Tom's idealism in his academic work. That idealism ultimately leads to a falling out between the two as Tom is on the verge of being demoted, and is appointed Designated Survivor for the next State of the Union address at the Capitol at which the rest of the cabinet will be in attendance showing their support. Tom is thrust into a full-fledged life of a politician when all the rest of the Cabinet, including the President, are killed in a bomb attack during that address, leaving Tom to assume the Presidency.
Taking into account his family who did not sign up for such a political life, Tom has to decide what to do about his and their future, and whether idealism has any place in the role of President. Conversely, the public may have its own thoughts of Tom as a non-elected President, especially if the imminent demotion ever comes to light. As time goes on, Tom's thoughts about what to do may change, which become all the more important when reelection time comes around if he survives that long in the position in whether he and the public will want him to have a second full term.
All the while, he has to restore public confidence in the aftermath of the bomb attack, which requires a secret service and FBI doing their part to discover what happened.