Everybody remembers the morning of September 11, 2001, when two passenger jets flew into the World Trade Center in downtown Manhattan. But the idea of toppling the towers was not new. Thirty years ago, a group of men set off a bomb in the garage beneath the North Tower, hoping it would tumble into the South Tower. At the time, this was the largest improvised explosive device ever ignited on American soil. It killed six people and injured thousands, leaving behind a 100-foot crater five stories deep. Investigators from New York City’s Joint Terrorism Task Force—a ragtag team of FBI...