When over-anxious actresses get talking, great things can come from it.

Take what happened when Karla Crome, former star of E4's cult hit, Misfits, met up with her friend Daniella Isaacs.

"We were both feeling depressed about our careers," Crome says, "because I'm a big worrier, and always think I'm never going to work again.

"Daniella was feeling the same way, and after we'd been to the theatre, we had a cup of tea, and she said she had this story about her 101-year-old Great Aunt Nancy."

Nancy Yetzes grew up Jewish in the East End of London. When she was in her twenties, she fell in love with a non-Jewish man who proposed to her.

Yetzes turned him down, worried about what her family and the local community might think. She has remained single ever since.

Crome's friend interviewed her Great Aunt Nancy about the experience, which ended up inspiring Mush and Me.

"Daniella's from the orthodox Jewish faith as well," Crome points out, "and we wondered if there was any value in trying to find a modern equivalent of what her great aunt went through."

The result of such speculation is the Edinburgh premiere of Mush and Me, Crome's Ideas Tap-winning play in which Isaac plays a young Jewish woman who falls for a Shi'ite Muslim man.

"It's basically a love story," says Crome, "and they embark on something of a secret relationship because of their different faiths, although in the end it's their difference in faiths that unite them."

It's 5am North Carolina time when Crome relates all this, already wide awake and up for talking before she goes off to work.

The 25-year-old actress is on location filming the latest episodes of Under The Dome, a small-screen adaptation of Stephen King's novel about what happens to the residents of a small American town after a giant dome cuts them off from the rest of the world. Crome plays a science teacher studying the dome.

After playing Jess, the girl with X-ray eyes who could see through everyone in the last two series of Misfits, another role in a fantasy show was perhaps inevitable. Not that Crome is complaining. Misfits was an inspired potty-mouthed cross between Heroes and Skins that followed the adventures of a group of youths on community service gifted with special powers following a freak storm.

"The scripts were hilarious," Crome says. "I laughed every day, and I met some of my best friends on the show."

Crome had already begun writing by the time she joined the show.

"I'd been farting about with it for years," Crome says, "and then the National Youth Theatre offered ten to twelve places to do a year-long playwriting mentorship. You had to submit a play, and I was accepted, and did that for a year.

"The interesting thing about that is that David Mumeni, who plays Mush, was also on the course, and we wrote together."

Out of this alliance came Our Days of Rage, a reaction to the Arab Spring, which was performed by the National Youth Theatre at the Old Vic Tunnels, with Isaacs playing the lead role. Our Days of Rage led to the NYT commissioning Crome to write If Chloe Can, a piece about young women's career options which has subsequently toured universities.

"I'd like to try again," she says of the experience of writing If Chloe Can while away filming. "It's a very stressful process, doing rewrites over Skype after you've started work at six and not finishing till eight, nine or ten.

"You've got to be passionate about the project to make it work but acting is the priority for me."

It has been since she was four, Crome says, when she would beg her mother to take her out of secondary school and let her audition for the Sylvia Young or Italia Conti theatre schools. Crome eventually went to Italia Conti aged eighteen, and not long after graduating appeared at the Royal Exchange theatre in Manchester. On television, Crome acted opposite Chloe Sevigny in Shameless writer Paul Abbot's six-part thriller, Hit and Miss.

Next came Murder, the BAFTA-winning TV drama that was the first English-language piece by director of The Killing, Birger Larsen. Crome played the lead in a straight-to-camera dissection of the killing of her character Coleen's sister and the trial that follows.

"It's the work that I'm proudest of and is most important to me," Crome says. "Coleen was angry, vulnerable, complex and everything you can get your teeth into as an actor. For a 23-year-old mixed-race woman without much experience, I've not had that many approaches to carry the emotional weight of something in that way since."

For all her anxieties about not working, Crome's head is full of people she'd like to play.

"I want to play a police-woman," she says, "I want to play a crack-head, I want a role where I have to get really fat."

Crome's dream role, however, is Amanda Wingfield, the disappointed matriarch in Tennessee Williams' play, The Glass Menagerie. While she might have a few years to wait for that one yet, it pays to plan early.

"I read somewhere that people who make lists are more likely to achieve their ambitions," she says. "At Christmas a couple of years ago I wrote down that I wanted to write a play and that I wanted to work in America, and now here I am."

Mush and Me, Underbelly to August 24