On a chilly October morning a small white mini-bus makes its way through the streets of Manhattan, transporting a group of journalists straight to prison.

Don’t worry, President Trump has yet to be elected (the US election is about two weeks away) so we're not being sent down for all that fake TV news we've been peddling. We’ve actually volunteered for a spell of Netflix-enforced incarceration at Litchfield Penitentiary, better known as the home of Orange Is The New Black.

The prison is situated in the bowels of an imposing white building in Astoria (just across the East River from Manhattan in Queens). When we arrive our ID is checked and our names are taken, before we’re escorted inside and guided through a series of corridors towards our holding cell for the day.

Filming on season five is well underway somewhere in this labyrinth and we’re not sure what to expect. Season four ended with a harrowing death and the beginnings of a prison riot after all, so who knows what’s happening in Litchfield now?

“Watch out for Big Bird,” a production staffer jokes as we make our way down a corridor lined with schedules, pay notices and all manner of administrative material for the team. “Who’s Big Bird?” I wonder, presuming this might be some new prison gang boss out to cause trouble.

It later transpires that we’re talking about Sesame Street’s Big Bird; the legendary children’s series shares some of the same production space.

Orange Is The New Black began life as the tale of a woman (Taylor Schilling’s Piper Chapman) who ends up in prison for helping an ex girlfriend smuggle drugs, but in the four years since its debut on Netflix it’s become so much more. The spectacular wall of framed magazine covers at the entrance to the production office is evidence of that.

“I knew when we made it that it was something very special,” says Taylor Schilling, “but I don’t think I ever thought ahead in the way that would allow me to conceive of it being what it is now.”

A map on the wall behind us, which details the layout of the prison, momentarily distracts her. “I’m going to take it with me and figure out a way to burrow out of Lichfield!”

The effect of Poussey Washington’s (Samira Wiley) death still hangs over the penitentiary, where a hallway has been transformed into a living memorial to the book lover. An archway of novels leads into a corridor that can only be described as a reader’s paradise, a quiet haven in the chaos of a prison riot.

Uzo Adoba, aka Crazy Eyes, hasn’t watched that fateful episode just yet. “I don’t need to watch somebody die again,” she says, revealing that she can still vividly remember what it was like filming the finale sequences.

"It was freaking insane," says Yael Stone (Lorna Morello) of the atmosphere on set the day Wiley and Adoba's pivotal season four scene was filmed. "It's eviscerating to watch your friends have to do that. To lose Samira was very hard."

The inmates left behind don’t have much time to stop and think about it all in season five though, as the story moves at breakneck pace. It’s told in real-time, following the women through a three-day riot in what Stone describes as a “really intense” series of episodes.

In the smashed-up prison there are some subtle hints, though. Posters calling for artists to volunteer to create a memorial for Poussey are scattered around the walls, while a list of prisoner demands (including Beyonce, Oprah and Netflix) has been drawn on panes of glass in the recreational areas.

The level of detail on set is stunning, with seemingly careless etchings carefully carved into the tables, used cotton buds placed deliberately on slightly greying sinks and organised chaos reigning supreme.

The queen of that chaos is writer Jenji Kohan, who enjoyed major success with Weeds before bringing OITNB to life.

“She’s an original mind,” says Kate Mulgrew (Red). “[OITNB] could go on for go on for 11 seasons of surprises. That’s her capacity. Her capacity is limitless. Her imagination is just so flexible, so vibrant, so dangerous,” she continues. “If she’s titillated, trust me: season six will surpass season five in its element of surprise.”

Mulgrew, who has been acting for more than 42 years, is – unsurprisingly – rather fond of her prison matriarch: “If this was the last role I were to play I would say to you how lovely that was.”

Her fellow cast members cherish this series too, but why do they think viewers have become so fond of it? “I think honesty and authenticity of the relationships is really what zings with people,” says Schilling. “I’m so thrilled that the show is touching so many people. I still am baffled by it a little bit.” 

Schilling is most proud of the fact that the show has tapped into a much bigger conversation about the US prison system. She and her castmates have learned a lot about the women's prison system through their work with advocacy groups, and would really like to see things change.

"It's atrocious," she says of the current set up. “Season five really opens it up. There’s less room for character development and it's more focusing on the political implications within the prison and outside of the prison of an inmate takeover.”

Perhaps that desire to challenge the status quo in a series that's become so much more than just another acting job for its stars is partly what makes them so happy to return to set when they're called.

There's a riot in progress after all, and a tight production schedule to adhere to, so as soon as the lunch bell rings our time inside is up.

As we clamber aboard the bus back to Manhattan, my only regret is that I never did bump into Big Bird. If I was caught up in a prison riot, I'd definitely want him to tell me how to escape to Sesame Street.