In David Koepp’s new thriller You Should Have Left, Amanda Seyfried plays Susanna, a young actress who, just before filming a big part in England, escapes to the Welsh countryside with her older husband Theo (Kevin Bacon). While inside the starkly modernist house (it could easily sit next to The Invisible Man’s spartan abode), secrets from their past start to show themselves in startling, sometimes phantasmagoric ways. It’s the rare haunted house movie where the characters are just as haunted. And it’s the rare Hollywood movie to address the significant age difference between the two leads.

So you can imagine how exciting it was to get to talk to Seyfried about her role in the film, the fact that it does so directly comment on such a well-worn Hollywood cliché, and what she found so alluring about being a part of the movie.

We also talk about Jennifer’s Body, her first entry into the horror genre and that film’s resurgent popularity, what it was like working on David Fincher’s upcoming black-and-white biopic Mank, and the possibility of a third Mamma Mia.

Collider: What appealed to you about this project? What kind of brought you to this movie?

SEYFRIED: It was the Kevin Bacon/David Koepp team. I remember knowing what it was about and being like, “Oh I don’t know. But then reading the script and be like, “Oh, that's pretty good.” And then meeting with David and Kevin, within five minutes, I decided that I really wanted to spend time with them. I was like, “I guess we're going to do this.” And this was like six months before we even started shooting. So I knew for six months that I was going to be working with them and I was really excited about it because they're really funny. And they've been friends for a really long time, since Stir of Echoes, and there's a lot of respect there and they had a lot of respect for me and it was just like, yes, I would love to be a part of this. I would love to make this a threesome. And it was even more fun than I expected. It was great. It was just a bunch of professionals making a movie that really meant something to each of them.

It's interesting because it's, it's the rare Hollywood movie that actually addresses the age difference between the leading man and the leading woman. Was that part of the appeal for you?

SEYFRIED: Yes. I know. I didn't really think about that as much. I mean, the appeal is really just diving into a pretty f’d-up marriage. And being a mother and being a really good mother and having a husband, who's a really good father, but yet you're hiding so much from each other that it could possibly never possibly pan out for them. I just love watching a train wreck like that. And I love playing it even more, because it's so meaty and there's so much to explore. which I just loved talking about scenes with other actors.

But I think also, in terms of the age gap, I mean, we do talk about it and it does make sense why she's with him and she's a little bit younger and likes. And she finds it really sexy that people find him dangerous and she finds him dangerous and she knows there's something living inside of him. And she's not quite sure what it is and she doesn't care because there's that whole appeal. I don't know. It is pretty realistic.

It’s just rare for a movie to address it directly.

SEYFRIED: It's so funny that he doesn't really feel that much older. I think my dad is like the same age as him and my dad also looks pretty young. And Kevin looks fantastic. He and Kyra are hot and I can't tell how old they are. You just can't. I'm in my mid-thirties and going to be 35 this year. So I don't feel like there was that much of a gap, but there is. There was it seen as weird. It's still seen as really f*cked up.

Did you have any favorite Kevin Bacon movies that you quizzed him about on set?

SEYFRIED: Oh, no. I did watch Stir of Echoes again. We were making it. I remember loving that movie and what’s the one where he’s invisible?

Hollow Man.

SEYFRIED: Yeah. Listen, I grew up watching him. I don't even know in what, like I grew up watching him and Kyra. It's weird to a point. And then you start spending time with that person when they become separate from the person that you watched growing up. But it's always great when you really think that somebody is fantastic and respect them and admire them as actors and then you get to work with them. Because you know, you know, it's going to turn out really good or at least it's going to feel really good.

Well, this is also your return to horror movies – your last true horror movie was Jennifer's Body, which has had this crazy reassessment over the last few years. What do you think about its legacy?

SEYFRIED: I'm proud of it. I'm not surprised that people really latched on and have come to appreciate it and created its own little fan base. I can't think of another movie that's similar to Jennifer's Body. Diablo [Cody] wrote something. I think that was very special and Karyn Kusama did a f*cking awesome job bringing it to life. You know, I was young and having fun. It was just so fun. I love when movies like that, especially when I'm so younger have, resurface or just have their own day and their own cult following, because it means it just lives on. I'm lucky I’ve gotten to be a part of a lot of specials movies. And this is no different. I think this is also not similar to other things. It’s very quiet, you don't know what it is for a while. And I think that's also really unsettling and adds to the fear factor. It's just the whole house, like stop moving. I hate when things are inconsistent. So there you go.

I wanted to ask about a couple of other things. You’re in David Fincher’s Mank later this year. What was that experience like?

SEYFRIED: Honestly, it is the hardest I've ever worked. But I am so thrilled with it. First of all, it came out of nowhere. Then I spoke with David Fincher … I had to download Zoom. Didn't know what it was. And I spoke to him for like an hour and a half hour about it, the script. I was pretty sure I was going to do it, but I didn't know, it was up to him. But I was just also like, how the fuck am I going to play Marion Davies? She had the accent. And how many takes? All of that stuff swarmed in. But I was also like, this is such a get - to work with Fincher he's one of a kind. And I actually can't believe we did it.

And we finished on February 21st, right before the quarantine. I can't believe it. And I was  doing three movies back-to-back, so each blended into the next and my head wasn’t was on straight. I was flying to LA on weekends and doing rehearsals with David and Gary, Arliss and all of the cast. And then like going back in for my other movies, It was great. And uh, yeah, it's going to be amazing. It's amazing.

How many takes did he make you do?

SEYFRIED: I think my … it wasn't so bad. I think maybe like … Oh, well I was part of scenes with tons of people in it and we would do it for an entire week. I can't tell you how many tastes we did, but I would guess 200, maybe I could be wrong and could be way off. Um, I could be underestimating by five days of one scene when I didn't have one line.

It's a, well, you think I can just relax? No, because there are probably about nine or 10 different camera angles that had been on me at one point.

Any artists you would love to do a Mamma Mia-style jukebox musical with?

SEYFRIED: I would, I do … if Patty Griffin had a musical based on her music, I would kill that shit. She’s in the folk crowd and she's huge. Some people are like, “Who?” And I’m like, “How do you not know Patty Griffin?” So maybe, maybe it'll never happen, but you know I would love that.

Have you talked about doing another Mamma Mia? Everybody loved the sequel so much.

SEYFRIED: Well it's a better story, because they had something to grow on. Like the first story had to match the stage show. So it was like, they were kind of stuck. With the second story, it could have been anything. Having Meryl’s character die kind of gave us so many good storylines. It was kind of a genius idea because you're like, no, we don't want to lose her. But at the same time, look at what you can do, you can go back. And Lily James can play young Meryl. It was just perfect. It was so well written. Listen, every single person in that movie would say yes in a heartbeat because we want to hang out with each other. That's what we talked about last time, like did we ever think that we'd end up here again on an Island in Croatia? So yeah, I wish there was a Mamma Mia 3, but I'll tell you what – I’ve said it before and I'll say it again and I hope I'm wrong again. I don't think there are enough ABBA songs to make a third movie. Because we'd have to use “Super Trooper” again and we'd have to use “Mamma Mia” again and have to use them in a different way.

You Should Have Left hits VOD tonight. Watch it with someone you’re comfortable grabbing onto.