S07:E01 - Voice of Terror

In the late 1970s, the FBI had a working knowledge of anti-Castro terrorists operating in the United States. But then a new group appeared, more violent and aggressive than their predecessors. All agents had to go on was a series of chilling phone calls, a mysterious voice, and the threat of more violence. FBI field offices from New York to Miami coordinated their efforts, determined to catch the vicious killers.