Executive producers Ron Moore and Maril Davis, along with stars Caitriona Balfe and Tobias Menzies, break down the major death in "All Debts Paid." Plus, get scoop on that shocking return not in the book.

[Warning: The following story contains spoilers from Sunday's Outlander, "All Debts Paid."]

Outlander fans may be used to saying goodbye to star Tobias Menzies, but this time, his onscreen death is sticking.

Not only did his sadistic soldier Black Jack Randall die in the season-three premiere, but in Sunday's episode, "All Debts Paid," his modern man Frank Randall also died, albeit 200 years later and in a much more heartbreaking way. Before he died in a car crash, he got into a nasty fight with Claire (Caitriona Balfe), ending in his demand for a divorce. Not surprising, given the fact that he's been seeing other women for the past two decades per his agreement with Claire, but he wanted more with this latest girlfriend. He wanted a real marriage, not the awkward and tenuous partnership he formed with the mother of "his" child.

Unfortunately, he'll never get to truly experience a full life with a wife who loves only him, as he died that same night. Claire broke down upon seeing his body in the hospital, and promised that she did love him very much. "You got my first love," she said, standing over his body.

As for her second love, back in 1766 Jamie (Sam Heughan) became the unofficial chief of all the men imprisoned in Ardsmuir, including a sickly Murtagh (Duncan Lacroix). John Grey (David Berry) took over leadership of the prison and was shocked to find the man who tricked him in the woods so many years before. At first he was embarrassed by Jamie's presence, but then the two men started to form their special bond, so much so that John made a romantic advance on Jamie. Still traumatized by his rape at the hands of Black Jack, Jamie threatened to kill John if he ever tried something like that again, and the two moved on from that awkward moment. A doctor helped Murtagh get better, and it seemed as if things were finally looking up for Jamie after the disastrous defeat at Culloden.

So when the prison was shut down, Jamie was crushed to learn that John couldn't secure his freedom along with the other men. As a consolation, John coordinated a job for him working at the Dunsany estate but only if he hid his name. And so began the next chapter of Jamie's life.

The Hollywood Reporter sat down with Outlander executive producers Ron Moore and Maril Davis, along with series stars Balfe and Menzies, to break down Frank's death, if Menzies will ever return to the show, Murtagh's return and more.

Is that the last we'll see of you on the show?

Tobias Menzies: That's it. It's strange. It's the end of three and a half years. I'll miss everyone very much. It's been a great journey. I worked hard on both of these characters. It was a challenge to make them different, but in a subtle way so it wasn't too obvious. I hope that it worked but one can never really know. My biggest takeaway, I think, is the friends I've made. All of them will stay in my life for a long time, so that's wonderful.

Is there a chance Tobias could return to the show in the future?

Ron Moore: You never know. I hope so. Not this season, but there's always other flashbacks or dream sequences or whatever. There's nothing planned but we're open to that possibility.

Maril Davis: It's hard to lose him. He's such an integral part of the show and he's done such an amazing job. We're such fans of Tobias just in real life, and it's hard losing a character you've grown to love and is so much fun to write for.

What was it like saying goodbye to not only Black Jack, but now Frank, all in the span of three episodes?

Caitriona Balfe: Tobias is such an incredible actor and has brought so much to both the characters that he plays. But to Frank, there was such heart to it. You really get to sympathize with this man. People say, "Oh, but he cheated and he did this," but his wife was in love with someone else and never stopped being in love with someone else. She came back pregnant with someone else's child so you can understand how he would need to go seek out comfort and intimacy with someone else, because that's what they don't have.

How will Frank's death affect Claire's moving forward?

Balfe: What I thought was interesting about where we see Claire at this point and her reaction to Frank's death, all of those moments, was that there's a repression to Claire this season that I don't think we've really seen before. I really wanted to play with that because she has had to close off a side of herself. She's more brittle and not always as sympathetic as maybe we've seen her before. When Frank dies, it's heartbreaking for her but it's almost as if she's not capable of those depths of feeling that she used to be because she's had to build up this wall around her heart so much. I'm hoping that as we go forward in the season that you'll see, once she meets Jamie again, that those walls start to get broken down and there will be a freer, more recognizable Claire that we've seen in previous seasons.

Before Frank died, he had some incredibly emotional moments with Claire where he finally asked for a divorce. Do you think he would have gone through with it had he lived?

Menzies: Yes, I do. Definitely.

What was it like filming that scene with Claire telling Frank's body that he had her first love?

Menzies: The writing was perfect for that so it made it quite easy for me to bring those scenes to life. It was always so great working with Cait. One of the nice things about doing a show for a long time, you get to grow together with another actor and get a real rapport. That's definitely true of Cait and I. Those scenes were fun to film.

Did it give that scene any extra gravity knowing it was your final moment on the show?

Menzies: Well, you can't really think about that. You have to focus on your lines, do the best you can.

When Claire says her goodbye to Frank over his dead body in the hospital, were you actually laying there for that scene?

Menzies: Yes, that was me. There wasn't a double body or anything like that. I had to try and not breathe. (Laughs.) It was pretty weird.

It was such a surprise to see Murtagh back this season, since he doesn't return in the book. Why did you make that change from the page to the screen?

Moore: I just didn't want to let go of the character. The way Murtagh's character developed over the first two seasons, he just became much more of one of the core characters than he was in the book. We played he and Jamie as a duo for quite a bit, their relationship was closer in the second season, they brought him in on the time travel secret, which is a big change from the book, so it just felt like, after all that time of making him an integral part of what was going on, I didn't want him to just die anonymously at Culloden. So after deciding he was going to live, we had to figure out how to bring him back and how we could tie him into the story going down the line. This is the character that we've established.

Davis: The books are pretty tightly woven in, so when you do pull out a string, it's sometimes hard to keep track. With Murtagh, having him not die in Culloden, you obviously couldn't bring him into Jamie's story earlier. He couldn't just be at Lallybroch. There are certain things that when you go off course, you have to figure out a creative way to get back on your path. We're still staying the line of the book but doing our own thing as well that may be off book.

Is Murtagh going to come back after this episode?

Moore: He'll come back. You'll see him again.

Now that viewers have met the older version of John Grey, given Outlander's success, is there any interest in exploring his story more in a spinoff down the road?

Moore: It's certainly something we've talked about now and again. There's nothing in active development but it's always a possibility.

Outlander airs Sundays at 8 p.m. on Starz.