While on vacation in London, Jack Ryan, a former CIA analyst, inadvertently thwarts an IRA terrorist attack on a member of the British Royal Family. His courageous act earns him the gratitude of the nation, but also makes him a target of the terrorists. Ryan's analytical skills, honed through his CIA career, allow him to anticipate the attackers' behaviors and successfully prevent the assassination. However, the terrorist leader, Sean Miller, is captured, and Ryan's role in foiling the attack is publicized, which leads him back into a world of security clearances and potential danger he thought he had left behind.

As the consequences of his actions escalate, Ryan's life and that of his family come under threat. Despite his attempts at returning to normalcy and his role as a history professor, he’s pulled deeper into the conflict. The attackers, seeking revenge for the disruption of their political cause and the capture of their leader, see Ryan as an obstacle to be eliminated. The situation becomes personal when the terrorists target Ryan's wife and daughter. This forces Ryan to confront the conflict head-on, using both his intelligence background and moral compass to protect his family and thwart further violence.