Mike and KITT travel faster than 100 mph in order to keep a hafnium bomb from exploding but, they are met with a few road obstacles on the way.  They are met by the cargo plane with Sarah and Dr Graiman aboard.  They cannot disarm the bomb but can climb high enough that it will become relatively harmless when it explodes.  Afterward Mike and Sarah get back in KITT to find the terrorist before he blows up a chemical weapons facility.  Dr Graiman stays aboard the plane to try and get it down safely.