Shes dangerous, unstoppable and hates the man who runs the family.

Heres Helen McCrory on Aunt Polly in Peaky Blinders series 4…

Contains spoilers forPeaky Blindersseries 4

Can you heal that?

The strength of the family is whether it can get together despite that and continue or not.

This series is about that test, says McCrory.

Her character, Aunt Polly, hates the man that runs the family, she continues.

Theres no stopping her.

She now makes her own decisions and that makes her really dangerous.

Does that mean Polly gets violent in this series?

I dont think she needs to, she says.

She doesnt hang somebody up in a butchers yard, she takes people down in a quite terrible way.

Peaky Blinderscreator and writer Steven Knight really, really, really explores Polly in this series, she says.

I think what develops this year is the best role that hes written for me.

Its the best series so far, says McCrory.

It continues to get better.

But how the hell do you get them back there?

Enter: the New York mafia.

Theyre the new threat forcing the Shelby family to retreat back to their Small Heath safe-hold in series four.

Finally introducing the mob is a very witty move by Steven Knight, says McCrory.

You get that idea of the big bear and the scrapping terrier and its an interesting fight.

Until their last-minute reprieve came through, Polly, Arthur, John and Michael faced execution by hanging.

It was a disturbing scene to film, McCrory tells us.

We spent a day on it.

You have to have only the other actor on, with a trapdoor.

It is very disturbing.

The answer is probably no.

Can you change yourself?

I believe, yes.

Polly does change in this because of this first experience.

Series four Polly wouldnt commission a portrait of herself as she did last time, says McCrory.

What does Polly want now?

Happiness and peace feel like a distant dream after the cliff-hanger ending to series fours first episode.

Thats not the only shock ending to expect this year, says McCrory.

[Steves] gone mad!

It sounds like you could say the same for Aunt Pol.

Peaky Blinders series four airs on Wednesdays at 9pm on BBC Two.