The airplane’s engine wailed, a high-pitched scream out of place even in the din of New York City traffic.

On the ground below, John Moran and a small crew of firemen were speeding toward the World Trade Center, toward the “small plane” that hit the North Tower about 20 minutes earlier. John was off duty, but he hopped in the truck anyway, responding to what most assumed was a terrible, unexplainable accident.

But then that screaming. The plane appeared seemingly from nowhere. It beelined for the South Tower, engines at full tilt.

This was no accident.

Commandeering a cab —punching the driver when he refused to move —John helped clear the Battery Park Underpass, ushering fire trucks and ambulances through to the crash site. Running into the South Tower, he looked over his shoulder and called to his colleagues: “I’m gonna see if I can make a difference in here.”

That momentary glance back was the last time anyone ever saw John.The announcement he was going to help were the last words anyone ever heard him speak.

His little brother, Mike, a fellow firefighter, worked 24-hour shifts scouring Ground Zero’s still-settling rubble for signs of life. But John was gone, one of the 343 firemen lost when the towers fell.