Second seasons of television shows are often referred to as sophomore seasons, which is especially fitting for “Back to Life” because showrunner and star Daisy Haggard considers her central character to be like a teenager in the new, six-episode journey.

“Back to Life” began with Haggard’s Miri getting out of prison after serving 18 years for killing one of her best friends, Lara Boback (Imogen Gurney). She moves back to her hometown of Hythe — and more specifically, she moves back to her parents’ house — to try to start her life. The small town around her hasn’t forgiven her for what she did, even though it was an accident, but Miri is determined to “find her feet,” as Haggard puts it.

“Miri needs to be an optimist. She needs that kind of, ‘You knock me down, I get back up again’ [attitude] and we layered that in. Then it started to take really a much better shape because you’ve got this protagonist who’s getting punched from all sides, but she’s determined,” she explains.

In some ways though, Miri was still “an innocent” in that first season, Haggard notes. It wasn’t until the end of those six episodes that she learned her friend Mandy (Christine Bottomley) had a sexual relationship with Lara’s father. Lara thought Daisy was the one sleeping with her dad, which led to a fight and the ultimately fatal accident. Learning the truth opened Miri’s eyes in a major way.

“This season is much more about her in the next phase. The first one was the her fledgling steps, her early steps, and in this one she’s got a bit more bite,” Haggard says of Miri.

It will turn out that Miri really needs that edge, not only in dealing with her new job working in a grocery store and finally learning to drive, but also when meeting the family of her new boyfriend Billy (Adeel Akhtar) and especially when Lara’s parents return to town.

“We certainly explore a feeling of real rock bottom and [of], ‘The world is against me, there’s no hope, it doesn’t matter what I did or who I am, this society has decided that I am bad and I’m never going to escape that.’ We definitely take that to a deeper level,” Haggard says.

The Bobacks (played by Lizzy McInnerny and Adrian Edmondson) moved away years earlier, but their reemergence now, just weeks after Miri has gotten out of prison, is no coincidence.

“He’s not a nice man. If he heard what was being said about him, he’s the kind of powerful person who would want to stop that,” Haggard says of why the former police chief returns to Hythe now. “I feel women are vilified in a different way when they do something wrong. This older guy had an affair with quite a young girl, and that was the reason behind [the death]. I think that’s the story I always wanted to tell.”

When crafting the season, Haggard says she and writer Laura Solon wanted “to make Miri’s life as brutal as we can possibly make it” by challenging her with a confrontation from parents who are still grieving the loss of their daughter almost two decades later. “Me and Laura were keen when we did the second season that it wouldn’t just be about Miri. These people had been through something terrible,” she says. “It felt important not to omit their grief.”

Even though the season will explore how “twisted” Mr. Boback (a.k.a. John) is, not only for his years-ago predatory behavior, but also for the way in which he tries to cover it up now, Haggard notes it was important to see “his pain as much as we saw his cruelty.”

“Forgiveness and redemption and many things like that that run through the show. With the darkness, it should have a big heart because that’s what I care about,” she says.

Haggard and Solon have infused Miri with this value. Although she is a character who did a terrible thing, it is not something about which she is in denial. She owns her mistakes and has done her time in the legal sense, but in many ways is still doing her time emotionally. A big part of the second season is Miri exploring how to push past her own complicated feelings about herself and let herself be happy.

For Haggard, the most important thing is that, through all the emotional swings as Miri stumbles through her arrested development, her journey feel “true.”

“When Laura and I are writing, we realize that Miri is the last character we have to pay attention to because both of us just think, ‘Oh Daisy will figure that out.’ And you get so obsessed with the story and the characters and everything else working and suddenly there’s a moment just before the read through where I go, ‘Oh my gosh, I haven’t looked at it as an actor,'” she says.

But, “because I’ve written her, in a sense, no one knows her better than me,” she continues. “When Laura and I write, we say, ‘Let’s read it out loud and see how it feels,’ so you’re working on the emotional journey the whole way through. And then if something doesn’t feel right, we change it. We create the pathway to what feels true and what feels right.”

“Back to Life” Season 2 premieres Sept. 13 at 10 p.m. on Showtime. The season has already aired on the BBC.