Why Orange is the New Black has been a life-changing experience for its actors

The darkly comic prison drama has had a major effect on some cast members, its stars tell Sarah Hughes

Laverne Cox plays transgender prisoner Sophia and is Orange is the New Black's breakout star

Laverne Cox is explaining how Orange is the New Black, which returns for its third season on Netflix this Friday, changed her world. "It just gave me this tremendous platform to speak out about issues that are important to me, and incredibly people are listening," she says, words almost falling over themselves in her enthusiasm. "My character is written with such humanity and depth, and that's touched so many people and opened their minds and made them see who trans people are. TV can be a wonderful tool, especially when the show is as complicated and nuanced as this one."

Cox (pictured above), who plays transgender prisoner Sophia, is Orange is the New Black's breakout star. In the three years since the comedy drama – an entertaining mix of witty one liners and serious points about the brutal reality of life in an American jail – began Cox, herself a transgender woman, has appeared on the cover of Time magazine, been hailed as an icon for her work raising awareness of the discrimination faced by transgender women, and black transgender women in particular, and gained an Emmy nomination for her sensitive and engaging turn as Sophia.

She's not the only member of Orange's large cast to have found her life transformed by the show. Danielle Brooks was barely out of drama school when she won the role of the irrepressible Taystee; this year she will take one of the three lead roles in a Broadway musical of The Color Purple, alongside Jennifer Hudson. The former teen star Natasha Lyonne had battled drug addiction for years before getting clean and mounting a career comeback as the sharp-tongued but kind-hearted Nicky. Uzo Aduba, who plays the unhinged but innocent Suzanne "Crazy Eyes" Warren, won the Emmy for Outstanding Guest Actress in a Comedy last year (beating both Lyonne and Cox in the process); next up is a leading role in the period drama Showing Roots, set in the Seventies.

Meanwhile Taylor Schilling, who plays the show's nominal lead, the self-obsessed Piper Chapman, has been freed from the prospect of years of blandly blonde supporting roles and handed the chance to play a true anti-heroine, a role she clearly relishes: "I love Piper deeply…there is such freedom in playing someone who is not endearing or doesn't colour within the lines," she says. "I also feel she's doing some things that wouldn't necessarily be as questioned if she was a man – no one questions whether Tony Soprano or [Breaking Bad's] Walter White should be likeable so I don't know why people get up in arms that there's a girl on TV behaving that way." Aduba laughs in agreement, adding that she actually feels very protective of her bantu knot-sporting alter ego. "She doesn't exactly break my heart because she doesn't feel sorry for herself but I do find it hard reading the scripts and realising that Suzanne just won't win. It's like watching a really awesome girlfriend who you know is with a horrible guy and they just keep going out and you're just like this is not going to end well."

The affectionate way all three actresses talk about their characters hints at why this particular drama has been such a huge success. On paper a series set in a woman's prison might sound drearily familiar, conjuring up long-buried memories of everything from Prisoner: Cell Block H to Bad Girls, but Orange Is The New Black tells its different stories with such style and panache that it's impossible not to get swept along, whether we're laughing at Taystee's fiction recommendations ["You ever read Outlander? Lady travels back in time to Scotland … hooks up with this big sexy outlaw type, and they be gettin' it day in and day out. Yo, it's hot!"] or crying for poor Suzanne desperately hunting for the chance to connect.

"I think Jenji's brilliance [Jenji Kohan is the show's creator] is that she never preaches," says Schilling. "The characters are so loveable and we care so much about them that when we get the social issues it's impossible for them not to touch your heart. Because it's not an issue any more: it's a person."

She's right. The series can make you laugh when you ought to be crying and can wring sorrow from triumph. It's a difficult tightrope to walk and the show could have flagged in its third year. Instead Kohan and her team make a triumphant return with an opening episode set on Mother's Day that initially appears as light and fluffy as a meringue, only to deliver a hell of a kick in the final few minutes. Over the course of the hour we are given fresh insight into favourite characters while learning just what motherhood means to a variety of inmates – from the orphaned Taystee, raised in children's homes and on the streets, to the former meth addict Tiffany Doggett, who aborted her children but can't let them go.

Most memorably of all we see Sophia connect with her son Michael, an awkward yet touching experience fuelled by the fact that Michael's mother is sitting in the car on Mother's Day while he talks to the woman he once called Dad. "I always cry whenever there's a scene between me and Michael," admits Cox. "It's weird because I'm not a mother in real life but I'm so connected to Sophia's motherhood and her love for her son. When I'm doing those scenes I think about my own mum a lot."

Yet it's not just tears and laughter, for Kohan also puts the question of motherhood under the spotlight, examining notions of privilege and looking at the reality of life for working-class women and the heart-breaking truth about being a mum and in jail. "I think that's the show's real power – the important points it makes even when we're having fun," says Schilling. "I've had people in jail tell me how closely the show parallels their experience. I hope it raises awareness and makes people think."

'Orange is the New Black', Netflix on Friday