- For the film see Patriot Games (Film)
Jack Ryan is vacationing with his family in London, when members of the Irish terrorist group, the Ulster Liberation Army, attack a nearby motorcade. Ryan, angered and offended by the violence, and acting on his training as a US Marine, runs into the street-battle. Jack shoulder-charges the closest of the terrorists, who was focusing on the passenger door or the main car, knocking him out and breaking his spine. Jack picked up the the handgun the man dropped, and shot him in the hip. He then went around the car, and tried to shoot the second man, missing. The terrorist turned, and both fired. Jack is hit in the shoulder, and the terrorist is hit in the chest. Ryan fires another shot into his head, killing him. The third terrorist escapes in a car.
A soldier runs up the Ryan with his weapon drawn. Jack drops the gun, and tells him what had happened. While the soldier is considering killing Jack, When his Daughter runs up to him and changes the soldiers mind. Cathy, Jack's wife, runs up to him. She begins to minister to him, telling the protesting soldier she was a doctor, and was going to treat Jack's wounds. A police officer comes by to tell Jack that the passengers of the car were the Prince and Princess of wales, and their newborn son, their first child.
This group later goes after Ryan and his family, partially as an act of revenge, but primarily because they seek to undermine public (and specifically American) support for their rivals, the Provisional IRA. The ULA plans a strike against Jack Ryan and his family. The assassin sent to kill Ryan is intercepted before he manages to complete his task, but Ryan's wife, Cathy, and daughter, Sally, are attacked by the terrorists who spray the car with gunfire, causing it to crash. Cathy escapes with minor injuries but Sally is gravely wounded and lies near death.
This determines Jack to take an offer the CIA had given him, to start working as an analyst in Langley, Virginia. Later, the Prince and Princess of Wales come to visit Ryan in America. This gives the ULA another opportunity to conduct another operation to weaken the support for the PIRA. They plan an operation, involving the killing of Jack Ryan and his family, kidnapping the Royal Family, and assassinating senior PIRA leaders—so the leader of the ULA could take over. The attack ultimately fails, and Jack and the Prince, with the help of Naval Academy midshipmen, coast guard and local police, arrest the terrorists on a freighter they had planned to use for their escape. Jack Ryan is particularly gratified that Miller ( who he almost executes with a Browning hi Power), who had incidentally killed a Maryland cop after attacking Ryan's wife and daughter, had been arrested after committing murder in a state with the death penalty: in the attack on the Royal Family, Miller had committed murder, but the U.K. had already abolished the death penalty, so he had been sentenced to life in prison. Presumably, The U.K. would not object to his trial and execution in the U.S. for a more recent crime committed there: they would not insist on his extradition to serve a life sentence in the U.K. before his execution in Maryland by gas chamber.
The novel ends with Cathy going into labor in the Naval Academy Dispensary, delivering Jack Ryan, Jr. This child will have two very different sets of godparents: Robby and Cecilia Jackson; and the Prince and Princess of Wales.