More than two decades on, Heat is still an important film.

We look at how Michael Mann’s research made for a powerful crime drama.

Origins

In 1963, detective Chuck Adamson sat down in a Chicago coffee shop with a convicted bank robber.

But in spite of his repeated brushes with the law, McCauley had no intention of going straight.

McCauley:I like Chicago.

McCauley:Well, look at the other side of the coin.

I might have to eliminate you.

Adamson:Im sure well meet again.

As the crooks attempted to flee the scene in a getaway car, Adamson and his partner opened fire.

When planningHeat, Manns meticulous attention to detail bordered on the obsessive.

We always had two guns, Elfmont said of these patrols with Mann.

Sometimes, I would hand him a gun, because he almost became like a partner…

Meanwhile, Tom Sizemore interviewed bank robbers in prison.

Ashley Judd interviewed their wives.

The actors were sent to an LA restaurant to eat and drink with cops and criminals.

They were taken to a bank in disguise to case the joint, just like thieves.

We cased the entire joint, Sizemore remembered.

I went and got a loan program, just to figure out what was going on in this bank.

It was a trip, how much knowledge we got.

And they didnt even know what was going on…

Although time-consuming and expensive, the training and education Mann put his actors through came out in their performances.

So much of his performance is in his eyes, which are suspicious and darting.

Even the smaller characters are invested with little details which bring them to life.

Married to the extraordinary, percussive music, and some astonishing sound design, its little short of unforgettable.

Its an intimate, uneasy and somewhat sad portrait of two men trapped in their individual fates.

I dont know how to do anything else, Hanna says.

Neither do I, replies McCauley.

He always said, Go as far as you might go.

Talk to the most extreme people you could talk to, get as much information as you could.'

By doing this, Mann created one of the great crime thrillers in cinema.