serious revolutionaries using far more lethal weapons. >> the '60s, we were all about changing hearts and minds. the '70s was more just about expressing anger. international politics and domestic politics seemed to be decided by violence. and violence only begets violence. >> from the underground, that radical left-wing group, the weathermen promises more attacks on the establishment around the entire country starting next week. the medium for this message was a tape recording reputedly by the weatherman rebel leader, bernadine dorn. >> sisters and brothers, we are not just attacking targets. we are bringing a pitiful, helpless giant to its knees. guard your colleges, guard your banks, guard your children, guard your doors. >> at one minute before 1:00 this morning, the switchboard at the capitol received a phone call. a man's voice said a bomb would go off in the building in half an hour. at 1:30 in the morning it did.