In The Line of Duty: Royal Warriors (1986)

When a state trooper is gunned down on a New Jersey highway, his friend and colleague sets out to track down the killers. Realizing the murder is connected to an extensive underground terrorist ring, he joins forces with the FBI on a massive five-state hunt.

Gordon Kahl is man who feels that the U.S. government doesn't care about the American farmer, so he retaliates by not paying taxes. He would be sent to prison and upon being released, his views have not changed. He encourages anyone who is having trouble not to pay taxes. He also joins a paramilitary and a white supremacy group. When the FBI learns of this, they try to arrest Kahl but Kahl, armed, doesn't want to go, and when the Feds don't let him go, he kills most of them. He then goes on the run and it's up to the FBI agent to headed the operation to find Kahl, and anyone else who may have been involved.

Arthur Milo, an IRS official with access to detailed personal and financial data, chooses his kidnap victims from his files. Pete Honeycutt is in charge of the case and Milo taunts him with personal phone calls, eventually threatening his family.