Marvel's Agents of SHIELD wrapped up its fourth season with a strong ending and one heck of a cliffhanger, which promises that the recently announced Season 5 will be out of this world.

To tie up some loose ends with Season 4 and get a sense of what we can expect from next year's SHIELD adventures -- and if there are any plans for this to be a final season -- I got on the phone with showrunner Jed Whedon and executive producer Jeff Bell to ask all the pressing questions.

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We're ecstatic. We love telling these stories and we feel like there are more stories to tell. We left the season on a cliffhanger so it would have been a bummer if we couldn't. There's more to come, and on a personal note, we love the people we work with, so we're really happy to keep the band together.We have a sense of how we'd like the show to end when it ends. We just need to know when that time is coming so we can build to it properly. Our characters have gone through some pretty big arcs over the past four seasons, and we hope to continue to do that going forward. If Season 5 is the last one, we'll build towards it, because when we know that we can adjust for that.Our goal is to know ahead of time, because we would love to land the story in a way that's satisfying and not have everybody going, "Aww, man!"I would say it evolves.Yeah, it evolves over time. Obviously when we were first talking about the show we had totally different ideas of who these characters would be and where they would go. That evolves when the actors bring what they bring, and when you run 88 of these you end up telling a lot of the stories you came up with at the beginning. It's evolved over time, so we'll see. It may evolve still.That was really a result of scheduling. We've always had at least a couple different story arcs, but people really did respond well to it. 22 [episodes], that's a long single arc to tell. I do think people responded well to the different types of stories, and I suspect we'll look at that again as we go forward.It's what it is. There was not a nice quiet shawarma version of it where they go, "Oh, it's nice to be together." It was always supposed to be, "Oh look, we're finally together. Oh no, something bad happens."It is!Man, SHIELD is not the coziest place to work, you know? I think they have a pretty good health plan, but other than that, it's kind of up in the air all the time.[silence] We can't say.We acknowledge there's a time jump.[silence] That's a good question.We can't say. Yeah, good question. Tune in! [laughs]To say he was happy, it would be an understatement.I think what he said when we told him was, "I didn't think I could geek out more," but he was like, "It seems I can."Yeah, that was what he said.We'll find out more about it, but I think it's safe to say he made a deal with the Ghost Rider, or the powers behind him. We'll see what it all means, but it didn't come for free. It wasn't like, "Hey bro, can I borrow that? Can I just borrow that Ghost Rider thing for a second?"Right, like borrowing a T-shirt.Well, first of all, he's not dead -- not that that means anything in our world. He also has shown that he has the ability to move in and out of realms and dimensions or planets or wherever he's going. He's a threat to pop up at any moment. Whether or not he will, I can't say, but he's out there.Umm... you can read into it what you will. That's all I can say on the matter.One of the things that's fun about playing in this universe is it keeps changing. The rule when we started was we couldn't say anything about spies, we couldn't say anything about Hydra, we couldn't have any A.I. or robots or anything like that, because all of that was coming in movies that year or the year after. Since then, they've blown those doors wide open. They've introduced magic with Doctor Strange, which we played with this year, and they've introduced deep, deep space with Guardians of the Galaxy.The sandbox we're playing in keeps getting bigger, and we want to explore all sides of it, and tell as many different stories as we can. Fortunately deep space is very different. We've gone there a little bit with Simmons. We felt like we enjoyed that, so maybe there's more to come.We have relatively free reign; we just can't go anywhere that they're going. They know their stories so much further out than we do, which is good for us to tee up things that we know are coming to them or avoid things that they want to be special on the big screen. As long as we are not covering bases that they're going to cover, we haven't been told "no" that much -- at least lately.The Framework's a great example of something that's pretty significant in our world, but is also a little eddy in the river that doesn't affect anything else because it's an alternate universe. So those kinds of stories help us go big without sending ripples through the whole MCU.First of all, it's the nature of the world. I think even this year with the flashbacks of May and Coulson and the rules we've stated through many seasons, that there are rules about agents not getting together for this very reason. Your love will be tested. That's sort of the nature of the business. I think it's safe to say from these past two episodes that they love each other and won't love anyone else, but that doesn't mean that they'll be able to repair their relationship and all that pain in between. One would hope that they could because everybody roots for FitzSimmons and the fans do and we do. We love the two actors, and so I think that seeing them together is a reward that the audience deserves, but how that happens, we'll have to wait and see if it does.I think the thing is people can have the forever love, but that doesn't necessarily mean they get to end up together. They might, but you don't know.But theirs is a forever love.I think Aida panned out for us much better than we ever could have wished for.I would say the great joy for us this season was our guest actors. We knew that our regular actors were terrific, but Aida and Mallory [Jansen] playing her, and Gabe [Luna] playing Robbie, and John Hannah, and though Natalia [Cordova] feels like a regular playing Yo-Yo, she's not. Those characters came in and surprised us in ways -- I mean, John Hannah came in for Season 3 and we realized, oh, he should be all the way through Season 4. And we brought Jason O'Mara in for a short run as The Patriot, and we realized, "Oh, we love him, we need to keep him around more." Mallory came in as Aida playing this very simple character, and we knew that she was going to grow and develop, but the places she took her were just a wonderful revelation for us.You took the words out of my mouth. The fun thing about TV is you move quick enough that you can actually react to what you're seeing in the performances. We kept throwing things at Mallory, and she kept fielding those balls, so we kept throwing more at her and waiting for her -- really sort of setting her up to fail, but she never did. [laughs]Also, just Gabriel Luna, having to come in and play a supernatural being -- or possessed by a flaming skull -- on a show with science on an international scale, and just grounding that character and giving it a weight and a pathos that felt lived in was also something that terrified us at the beginning of this season. Mark Kolpack and his visual effects team delivered the flaming skull in a plausible way, but it was really Gabriel's performance that made it all seem real.Mr. Bell can not overstate how afraid we were of Ghost Rider. [laughs] Tonally, fitting that on our show, to us, felt like a great danger of a square peg hitting a round hole, and you're right that Gabe helped it move effortlessly into our world. It felt like a great escalation and not a mashup.Along those same lines, one of the things we really strive for is there are several things we do each year that just scare the hell out of us. Like, this could be an epic failure, but we're trying to tell stories that are surprising and doing something we haven't done before. Sometimes you don't know until you see the visual effects or till it's cut together that what we're trying to do is actually going to work. I think we really, in a weird way, get off on trying to stretch those boundaries every season and every episode.When we're tossing around ideas in the room, you always know it's a good idea when everybody goes, "... Yes?"We're all, I think, properly terrified of what we're doing next season the way we were properly terrified going into this season. [laughs]Bait-and-switches aren't as fun.Your question is like: "Are you going to do something cool, or is a sucker thing and we're going to be really sad?""Are you guys good people or bad people?"[laughs]He's either in outer space, or he has just such a really nice new television, and he has to get back to work to pay for that 4K image outside that window.

Editor's note: This interview was conducted prior to the announcement that Marvel's Agents of SHIELD will be airing during ABC's midseason on Fridays , following the conclusion of Marvel's Inhumans ' eight-episode run.Terri Schwartz is Entertainment Editor at IGN. Talk to her on Twitter at @Terri_Schwartz