In a crowded London underground station, a small routine fire suddenly erupts into a deadly inferno and kills 31 people. Dozens more are injured.

A team of forensic experts searches for clues to the cause of the blaze and finds that the fire seemed

to defy the very laws of physics.

To unravel the cause of the mysterious fire,

investigators would need to recreate

a historic train station

inside a modern computer.

So, The Sprawling London Underground is the largest and oldest subway rail system in the world.

But on the evening of November 18, 1987, commuters are unaware that disaster lurks beneath them.

At 7.30 p.m., a passenger at the historic Kings Cross Station sees a flicker of flame underneath a heavily varnished 50-year-old wooden escalator.

The London Fire Brigade is dispatched. It seems to be a routine call.

An everyday call to a fire and escalator is something we were receiving probably 20 or 30 times a month. So it was no big deal.

Fire captain Roger Kendall, one of the first to reach the scene, waits above ground for his supervisor to report.

We were waiting for a message to come back to say that we're all going home or he may need a bit of equipment.

Trains continue to come and go, despite the minor commotion.

Musician Ron Lipsius arrives at the station on one of those trains.

We've noticed these two men, I don't think they were in uniform,

but they were blocking, physically blocking,

entrance to the wooden escalators on our left,

which are the ones that directly go to the

Piccadilly train. So we thought, oh, that's strange. And it was actually a tiny bit hazy in there,

too. We noticed that, too. A little bit smoky. Firemen see a small fire burning about halfway up one of the escalators bringing passengers

...