Patriot Games (1992)

Plot:

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.