 Jack Ryan and his family are vacationing in England. Quite by accident, Ryan thwarts a terrorist attack - outside Buckingham Palace on Lord Holmes, a member of the royal family - by a splinter IRA group, killing the younger brother of one of the terrorists. Retuning to the U.S. with his family, Ryan thinks that s the end of the matter. But the terrorist won t let the matter rest and he won t stop until he s had his revenge.