Lincoln Rhyme knew, though, that those fringe Muslims were a very small portion of the people who had ideological gripes with the United States and were willing to express those views violently. And most terrorists were white, Christian card-carrying citizens.

The history of domestic terrorism is long. The Haymarket bombing occurred in Chicago in 1886. The Los Angeles Times offices were blown up by union radicals in 1910. San Francisco was rocked by the Preparedness Day bombing, protesting proposed involvement in World War One. And a horse-drawn wagon bomb outside J.P. Morgan bank killed dozens and injured hundreds in 1920. As the years went by, the political and social divisiveness that motivated these acts and others continued undiminished. In fact, the terrorist movements grew, thanks to the Internet, where like-minded haters could gather and scheme in relative anonymity.

The technology of destruction improved too, allowing people like the Unabomber to terrorize schools and academics and to evade detection for years, and with relative ease. Timothy McVeigh manufactured a fertilizer bomb that destroyed the federal building in Oklahoma City.

Presently, Rhyme knew there were about two dozen active domestic terror groups being monitored by the FBI and local authorities, ranging from the Army of God (anti-abortion), to Aryan Nations (white, nationalist neo-Nazis), to the Phineas Priesthood (anti-gay, anti-interracial-marriage, anti-Semitic and anti-taxation, among others), to small one-off, disorganized cells of strident crazies called by police ‘garage bands’.

Authorities also kept a watchful eye on another category of potential terror: private militias, of which there’s at least one in every state of the union, with a total membership of more than fifty thousand.

These groups were more or less independent but were joined by common views: that the federal government is too intrusive and a threat to individual freedom, lower or no taxes, fundamentalist Christianity, an isolationist stance when it comes to foreign policy, distrust of Wall Street and globalization. While not many militias put it in their bylaws, they also embrace certain de facto policies like racism, nationalism, anti-immigration, misogyny and anti-Semitism, anti-abortion and anti-LGBT.

A particular problem with the militias is that, by definition, they’re paramilitary groups; they believe fervently in the second amendment (‘A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed’). Which meant that they were usually armed to the teeth. Admittedly some militias aren’t terrorist organizations and claim their weapons are only for hunting and self-defense. Others, such as Matthew Stanton’s American Families First Council, obviously felt otherwise.

Why New York City should be a particularly juicy target Rhyme had never figured out (the militias, curiously, pretty much left Washington, DC alone). Maybe it was the other trappings of the Big Apple that appealed: gays, a large non-Anglo population, home of the liberal media, the headquarters of so many multinational companies. And maybe they felt the Rockettes and Annie carried thinly veiled socialist propaganda.