July 6, 1944: 7,000 people, mostly mothers and children, sit beneath the largest circus tent in America when the band suddenly strikes up a march that performers know as the disaster signal. Within eight minutes, the canvas world is destroyed and at least 167 people are dead.

This deep dive pulls apart the mechanics of the Hartford Circus Fire, from the wartime decisions that turned the tent into a fire bomb to the unbelievable acts of rescue. We also confront two enduring mysteries: how the fire ignited, and the true identity of a child known only as Little Miss 1565.

• The tent was waterproofed with 1,800 pounds of paraffin wax dissolved in 6,000 gallons of gasoline because the military had requisitioned fireproofing.
• Exits were blocked by metal animal chutes, and normalcy bias kept many seated until the crushing congesti ...