For the past three seasons, Boardwalk Empire fans watched Gillian Darmody (played by the luminous, underrated Gretchen Mol) engage in an incestuous relationship with her son, murder a one-night stand in cold blood, order a hit on her lover and generally lie, cheat and steal her way to the middle. In other words, the character had gone beyond redemption.

Or so we thought.

When the HBO drama kicked off its fourth season last month, we were introduced to a drastically different Gillian, one who was powerless, vulnerable, broken and, most startling of all, filled with regret. Before we knew it, we were starting to feel sorry for this vile woman.

Her climb out of the depths of depravity is accelerated in this Sunday’s episode when the new man in her life, Roy (Ron Livingston), helps her kick her heroin addiction cold turkey. Below, Mol opens up to TVLine about Gillian’s past transgressions, current turnaround and future happiness.

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TVLINE | Are you enjoying playing this new side of Gillian?

It’s been wonderful. I’ve always approached her as a whole person though, not just as a kind of [evil] archetype. But it’s always nice to reveal other colors to the characters you play. I remember when we were shooting one of the first scenes [this season], which was Gillian at Chalky’s club with Roy, she’s just listening to the music and I thought “Wow, Gillian’s out in the world and smiling — we’ve never seen her enjoy and let herself be swept away by anything!”

TVLINE | This definitely feels like a “Redemption of Gillian” arc.

The fact that she’s having trouble and that we’re seeing her struggle — she struggled before but it was really just about power — helps build some kind of sympathy; it makes her kind of a human being.

TVLINE | In this Sunday’s episode, Roy — as he’s helping Gillian quit her heroin addiction — tells her she looks like she’s at peace. Given, everything she has done, can she ever really be at peace?

Good question. I don’t really know if peace is in the cards for Gillian… Yes, she has done horrific things: She really hurt her son in Season 2. And then [murdering] that poor, innocent Jimmy look-alike Roger (Billy Magnussen, pictured) was really beyond. But [there’s] so much violence [on the show], I think it’s interesting that the writers have chosen to pay so much attention to that murder. It’s an interesting social commentary that this woman does this one thing and she has to pay for it, while all of these guys are [considered] heroic for the murders that they [commit].

TVLINE | Yeah, when a woman kills someone, it’s a bigger deal…

I actually didn’t watch Breaking Bad but I remember reading the op-ed piece [in The New York Times] by Anna Gunn and I could kind of relate to it. I know that there are a lot of people who love Gillian, but when people have that kind of vitriol, it is a little bit scary. I think it comes out of fear.

TVLINE | What do you think caused this shift in Gillian? Was it meeting Roy?

I think that it’s probably the addiction that shook things up. I think that the drugs kind of got her; she’s powerless to them. And there’s something about the choice of heroin… it’s sort of the perfect drug for Gillian because she can finally let go of all that struggle and allow herself to be open to this newcomer. Whereas I think she may have been too cynical or disbelieving or just not open to that kind of a man [had she not been on drugs]. She may have seen him more as someone to be conquered, someone to be used. I think now she’s just so down, and has lost any kind of power that she had, so she’s vulnerable and open to it. Maybe in that way heroin is a good thing [Laughs].

TVLINE | As I watch that story unfold I find myself really rooting for Gillian for the first time.

I’m so happy!

TVLINE | But this is Boardwalk Empire, so I also know it probably won’t end well for her.

[Sighs] I know, I know… Gillian has had such a tough life, and it just feels like she doesn’t have the tools to really know what’s good and what’s bad. Her ability to outsmart in a situation right now is not the sharpest.