Three Heartbeats Away

The president, vice president and Speaker of the House are all assassinated on the same day, at the same time but at different locations. A newly surfaced terrorist organization takes immediate credit for these horrific acts. Their leader is not your typical fanatical extremist but rather a highly educated murderous mastermind. The third individual in the line of presidential succession in the United States is the president pro tempore of the Senate. That someone, who was three heartbeats away, just became the leader of the free world. Demands are made but should the United States meet them to evade threatened catastrophic events? As America is being held hostage, certain top U.S. officials turn toward an elite CIA operative team as their only hope in putting an end to this mayhem. Could this really be happening?