It was supposed to be a routine motorcade for the Queen of England. But on the way to Yosemite National Park, a car carrying three Secret Service agents collided with a car driven by a deputy from the local sheriff's office. The agents were killed instantly. In the investigation which followed, two teams oaccident reconstructionists reached very different conclusions. It would take a court case and a judge's ruling to determine what really happened, and who was responsible. (thetvdb.com)