Kate Mulgrew has been acting for 42 years. During that time, she has had several memorable roles, including Kathryn Janeway in Star Trek: Voyager and Mary Ryan in Ryan's Hope. In 2013, however, she started work on Netflix's Orange is the New Black, and found a character she has 'kismet' with: the redoutable, red-haired Russian matriarch of Litchfield Penitentiary, Galina 'Red' Reznikov.

'I've been acting for a long time,' she says authoritatively, 'and I know content by now. I know when the writing is exemplary and when it is extraordinary, and it is both in this case.

'Red just jumped off the page and into my imagination, which very seldom happens. It was organic, it was authentic and it was a feeling or real joy which seldom comes in a creative life.'

Mulgrew originally auditioned without reading the full script, but knew right away that there was something special about the show and the character in particular. 'Usually when you have a great role and you play it for a long time the love affair is very fast, as is true in life. If you don't have that instant foundation you don't really have much to work with.

'With Red I knew instantly I would love her for a long time and I could develop her accordingly. I had that opportunity with Jenji [Kohan, the show's creator and writer] behind me. It's one thing to create a voice and it's another to sustain it, but not only has she sustained it, she has embellished it to such an extent that Red's is one of the clearer and more unusual voices on television.'

Mulgrew's connection with her character sometimes leaks into the conversation: on more than one occasion, the actress talks as though she is Red, using the first person to discuss what's coming to 'her' in season four (released on Fri 17 Jun).

'I have risked much to survive,' she says, 'and you will see new skills brought to bear on Season 4. You are going to see the tsunami come. Not everybody survives the tsunami. There's a seismic change taking place at Litchfield. It will have a domino effect, and only a few will be left standing in accordance with their own moral code. I believe I am one of them.'

The new season's tagline is 'new blood, new rules', and it sees a new influx of inmates as a result of the prison's privatisation. But even with a host of new characters to learn about, and new stories to tell, Mulgrew isn't worried about Red fading into the background. 'You don't have to worry about keeping Red relevant. Relevance does not apply to Red. She finds a way to make it work for her, that is the essential Reznikov.'

One thing that will not change this season is the value the show places on women's stories. With 50 inmates, and 50 potential stories to tell, Orange is the New Black champions female struggles in an incomparable way. But are women's stories shared enough in film and TV?

'It's getting better,' Mulgrew says. 'But no. I don't think there's enough. We're 51% of the population but it's still a boys club. We need to keep battering away at it.'

Arguably, the show is battering away at key issues one-by-one, with everything from abortion to sexuality and gender identity covered through its myriad of characters. This, Mulgrew believes, is due to the excellence of Kohan's writing, and the strength she has as a storyteller.

'Why not write about the great issues?' she says. '[Kohan] is a girl who is alive. She's looking at the world we live in with a cool keen eye. She's forcing us to look at it too, and as we do, we're absolutely riveted.'

And when you feel this passionately about the character, and the script, it can he hard not to take it home with you. 'For six months when I'm filming, I'm rather impossible to be around,' she says. '[My family] laugh at me, and tell me to get over myself. I say "no, go in the kitchen and get me a martini".'

If Orange is the New Black has taught us anything, it's that you'd better do what Red says.

Orange is the New Black, Season 4 is avaible on Netflix from Fri 17 Jun.