Warning: This article contains spoilers for Matlock season 1, episode 12, "This Is That Moment."

Matlock just revealed a key moment in Madeline's (Kathy Bates) backstory — and gave us our first look at the most important figure from her past.

Episode 12 of the CBS legal drama, titled "This Is That Moment," reveals our clearest glimpse of Matty's late daughter, Ellie, in unprecedented flashback sequences that depict the titular lawyer fighting for custody of her grandson, Alfie (Aaron D. Harris). Marnee Carpenter (Clarice) portrays Ellie, whose addiction to opioids ultimately ends her life in an accidental overdose — and fuels Mattie's undercover revenge mission as she investigates the Jacobson Moore law firm in an attempt to find out who withheld crucial information that could have ended the opioid crisis.

The new episode reveals that Matty's custody battle was a driving force in Ellie's death, as she'd been clean for a month but ultimately relapsed in the midst of the hearing, leading to her overdose.

Entertainment Weekly spoke with showrunner Jennie Snyder Urman about the bombshell episode, how Kathy Bates helped shape her character's backstory, and what to expect from the future of the show.

ENTERTAINMENT WEEKLY: How did you and the writing team decide when would be the right moment in the season to first show Ellie?

JENNIE SNYDER URMAN: Well, we wanted to really have the audience know a lot about her and her effect on Matty and just all the different ways that she shows up before we introduced her, so that she could really live in the audience's memory solely through Matty at the beginning — so that their whole experience of her was this sort of absence. But they would hear about her a lot and the characters would be talking about her a lot, and she would come up emotionally. So, really, to whet the appetite so that when you finally meet her, it means something. And then to meet her in this specific circumstance, you realize what the ultimate pain is that Matty is trying to cover up and make amends for.

Kathy Bates on 'Matlock'.

Sonja Flemming/CBS

Was there any version of Ellie's introduction that didn't involve the custody hearing as her first appearance?

There wasn't, but I will say though that when I was talking to Kathy Bates early on, before we started doing the season but after we had done the pilot, she was the one who said to me, "I think when Matty tried to get custody, that's when Ellie died." And she put that into my head. And when you hear an idea that's just right, you have to do it. And that was one of those moments when Kathy said something, it unlocked something for me and I was like, "That is the way it must be." I hadn't known that Ellie was going to die around the custody battle. So when we came into the writers' room, then we developed that it was the day of the hearing, and that Ellie wouldn't be there — all those plot points.

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Did Kathy indicate where that idea came from?

I think it was her metabolizing the character and thinking about it a lot. And we talked extensively about what the loss of Ellie meant for her. Kathy has a lot of brilliant ideas, and I think this was one of them. When she was doing her homework for the character and developing the character and what would propel her to do such an insane scheme and infiltrate a law firm and try to expose them — we knew that there had to be something so deeply painful. And I think probably in creating that character, that circumstance came up for her.

How did the casting process for Ellie work?

We have amazing, amazing casting directors, and Marnee was in our first batch of auditions that they sent us, and she was everyone's first choice — the writers, David Aguilar and Jeffrey Lieber, and our director, Kat Coiro. And then we showed her to Kathy, and Kathy just said, "It has to be her."

Her audition was very close to what the performance is in the show, and she just had a real vulnerability and you could feel a lot of the pain of Ellie's life of the last eight years in that actor's performance. She really sold us on both what she wanted and what she'd been through, and she just made us emotional. You wanted to hug her and say, "You can do it. You can get through this."

Leah Lewis, Skye P. Marshall, and Eme Ikwuakor on 'Matlock'.

Michael Yarish/CBS

How did you and the writing team go about crafting Matty's testimony on the witness stand?

It was a lot of research into both addiction and what you do as the parent of an addict, and when you draw the lines. It was a very painful thing, which was that Matty loves her daughter, but she has to say in open court that she doesn't think she is a fit mother, and at the same time, she knows that this kid is Ellie's tether to getting better. So all of that sort of complicated her testimony, but she had to put her grandson's well-being on top of everything. 

And so those are all the layers that I think you see Kathy operating. It switches in an instant — she wants to reach over and hug her daughter, but she also has to hold this really strong boundary and make sure that her grandson's safe. You can see years and years of being pushed to your limit, I think, in her face, and also a real hope that maybe this will be the thing that changes the course of her daughter's life. 

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Matty's description of infant withdrawal is probably the heaviest moment in the show so far. Did you feel the weight of the subject matter while in the process of researching addiction?

Yeah, definitely. This is a heavier episode overall. It's got to be — we can't go as light as we do in other episodes because this particular one is dealing with so much. So yeah, it's heavy. We had an addiction specialist talk to us, and also various writers' personal experiences also went into that moment. When thinking about this episode for a couple months before we did it, it always broke my heart just thinking about what it would mean for Matty. Her side of the flashbacks were an easy journey to break, because we knew what happened, but it was a heartbreaking journey to break. And there were definitely moments because you care about your characters that you're just like, "Oh my God, she has to live with this. This is so painful." 

Were there any specific elements or details about the addiction side of the story that you felt a particular responsibility to depict accurately?

All of it. Everyone's journey with addiction is a little bit different, but there are these same things that happen when you're in it. And a look at addiction is really important for the whole series. I don't want to give away too many spoilers, but at a certain moment, somebody says to Matty, like, "This is your addiction, this thing, this job. Are you lying to people so that you could do more of it? Are you changing your moral center so that you can do more of it? This has become your addiction so that you don't have to deal with other pain." So there are different kinds of addictions, and we've layered in that Matty's mother was an alcoholic as well. So our whole show wants to look at addiction, I think, with compassion.

Kathy Bates on 'Matlock'.

Michael Yarish/CBS

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Do you remember how Kathy reacted upon seeing these flashback scenes on the page?

She really thought that they were heartbreaking and really liked them, and also was like, "This is so many complicated emotions that I have to play." And she's a rigorous prepper in the best way. Since she had given me that initial idea, I knew she was anxious and excited to get to this episode because we knew it was going to be this turning point. So yeah, it was exciting. Everybody felt very safe and excited to do it.

How much of this backstory from this episode do you reckon that Alfie is aware of? 

We've talked about it a lot. I think that they've been honest overall. I mean, we haven't committed to that moment, so there's always a chance that in our next year storytelling we might go, "Oh, but there was this one detail he didn't know," but he knows the breadth of his mother's story and how he ended up there and with his grandparents, and I think it's something that they do talk about a lot in general.

Should we expect to see more of Ellie depicted on screen? 

You won't see her for the rest of the season, but you will see her in the upcoming season at another sort of seminal turning point, and you just continually learn more about who she was and her relationship with her mom. 

Will we see any more flashbacks of this size this season?

There's one more. We had planned these three moments. [Olympia's divorce, Ellie's death, and a third.] Kind of every six episodes or something. There's a different kind of flashback coming. It's a little bit more fantasy.

Matlock airs new episodes Thursdays at 9 p.m. ET/PT on CBS.

This interview has been edited for clarity and length.

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