Michael Gann’s attempt to plan a mass-casualty incident in New York City came to pass with the terrifying accuracy of a nightmare that was only barely avoided.

Those who keep an eye on the data points that the rest of the world overlooks frequently draw the line in the shadows between a typical Tuesday and a generational disaster in the high-stakes realm of counterterrorism. For Michael Gann, the goal was to completely destabilize the most famous city in the country; for local and federal investigators, it was a race against a time that only Gann knew was running out.

The plot’s scope and level of cruelty were astounding. Later, investigators discovered that Gann had actually started the tactical deployment of his armaments, not just planned an attack. IEDs, or improvised explosive devices, had been carefully dispersed around the city’s most susceptible thoroughfares. These placements were not made at random; rather, they were the product of a guy who had researched the pulse of the city.

Devices were found around crucial subway track sections where the subsurface topography would have increased the explosion’s concussive effect. They were located on rooftops and in high places, where they could maximize an unavoidable sense of terror and shower debris down on busy streets. Gann had a very clear goal in mind: to use New York City’s infrastructure against its citizens.