In 1995, FBI profiler Jim "Fitz" Fitzgerald joins the Unabom Task Force. Fitz recommends new methods of profiling but finds no allies among the agents in charge. In 1997, Fitz is tasked with confronting Ted Kaczynski, the Unabomber.

When the elusive Unabomber threatens to blow up a jetliner, Fitz must determine if the threat is real. In 1997, Fitz confronts Ted for the first time.

Linguist Natalie Rogers helps Fitz find clues about the Unabomber's identity in the Manifesto, but their findings face skepticism at the UTF. In 1997, Ted claims he can invalidate all of the evidence against him.

The Unabomber will stop bombing if his Manifesto is published. Fitz pushes for publication with S.A.C. Ackerman, who presents Fitz's argument to Attorney General Janet Reno.

Fitz receives linguistic proof that Ted is the Unabomber. He tracks down Ted's brother David, who is astonished at the accuracy of Fitz's profile.

In a letter to his brother, Ted recounts the key events from his past that informed his decision to engage in terrorist activities.