A nearly three-hour German comedy about a mischievous father and his straightlaced daughter does not exactly scream “runaway hit,” but that’s been the odd trajectory of Toni Erdmann. Since its vaunted premiere at the Cannes film festival this past May, this touching, uproarious, totally singular film has been tracing an upward arc from the international arthouse to the stratosphere of the global mainstream. It’s been lavished with acclaim wherever it’s played. It’s been topping best-of-the-year lists internet-wide. Now it looks poised to compete for the Foreign-Language Oscar—and pundits insists it’s the film’s prize to lose.

None of this success will come as surprise to those who’ve actually seen Toni Erdmann. In the popular imagination, the average foreign art movie is woefully serious and grave, but this one is a crowd-pleaser through and through. The story of a young German businesswoman, Ines (Sandra Hüller), and the eccentric dad, Winfried (Peter Simonischek), who arrives to shake up her all-consuming job at a fast-paced Romanian consulting firm, Toni Erdmann is hysterical, outrageous and brisk even at 162 minutes. The movie really has it all, including family drama and wild sex and corporate intrigue. It has costumed antics and naked brunch parties and giant Bulgarian monsters made of fur. It has a Whitney Houston singalong.

As the film hits theaters across the United States this week, we caught up with Toni Erdmann’s writer-director, Maren Ade, to talk about day jobs, power structures and how hard it is to sing “The Greatest Love of All.” Note: mild spoilers ahead.

This isn’t a movie about corporate consultancy and international finance, but those aspects of the film are unusually well-developed. Is that a field that interests you?
It’s something I really wanted to understand. There was a lot of research involved in making the film, and I spent a lot of time talking to businesswomen and people in the industry. In the beginning, though, I hadn’t quite decided what job the main character would be doing—and I also met with many women in other lines of work, such as people who help form companies. But I found this job of the consultant really interesting.

In what way?
The world economy doesn’t work without consultancy companies anymore, but hiring them is always an outsourcing of responsibility. I found that really typical of our generation: It’s not so easy to find out who’s responsible for what anymore. Things have become too complicated. On the other hand, I liked that there is so much performance involved, even necessary, in the work. It’s necessary that Ines plays such a strong role in her job, and it becomes complicated for her to leave that role aside in her private life.

I thought it was interesting that when Winfried leaves the film, he’s gone just long enough that—
—That you think he’ll never come back? [Laughs] Yes, that’s exactly what I wanted. You think, “Oh no, the movie is about to get so much more boring now!”

The first time you see the film his reintroduction is such a surprise, but rewatching it I noticed that you can actually see him much earlier: He’s there lurking in the background.
Yeah, yeah! I wanted it to be really precise—to stage it in such a way that it would be possible for you to see him when you went back and studied it closely. If you watch the film a second time, yes, it’s clear, he’s there: that’s something that I wanted. Though I do hope that it’s really a big surprise that he appears like that…

Because the effect of the surprise is so important.
Exactly. I always had this idea in mind that Winfried is coming back and starting a new movie, in a way. Almost like he says, “oh no, this father-daughter drama I was in is not the one that I like — let’s try a new film.” I sometimes have the feeling that we are all longing for something like that, you know? We want to be in a better movie than the one we’re in.

It’s been 13 years now since your first feature, The Forest for the Trees—which was technically a student film, though maybe the most accomplished student film ever. How’s your process changed since then?
It didn’t change so much as the process got more extensive. The actors are still very much in the center, and I try to arrange everything around them. But when you do your first film you find out things, things go wrong, and you say: This will never happen again. For me I found that it’s good to have as much rehearsal as possible. It’s good to stage a scene if possible at the actual location. The big step from the second film to the third was the scale: There were so many more actors involved, so many more locations. Sometimes I had the feeling that it was really a bit too heavy, what I was trying. I’m relieved it worked.

We want to be in a better movie than the one we’re in.

One thing that strikes me as similar in all three films is this idea of shifting sympathies.
Yeah, yeah. When I have two characters I always try to get both perspectives together. Sometimes I succeed and get both sides; other times it feels right to have just one perspective. And it changes, when you watch the film a second time: Suddenly you agree with the other person. I try to treat every character equally. It has to be rich under the dialogue. Because that’s the story: In my films, the story doesn’t happen on the surface.

It’s more about the power structure underneath.
Power structure! Yes. That’s a good term. One thing I’m interested in: hierarchies. When you have four people in a room, immediately, when you look more closely, people arrange themselves in terms of status. There are a lot of unspoken things going on between people from moment to moment — especially when their status switches. You can see that happening in the film. When Winfried creates Toni, he reaches the same status as Ines.

How you can be sure that an audience will find the power balanced scene to scene? Or that their sympathies will be where you need them to be?
I don’t work with audiences. I try to rely on my own feelings. But it already has to work in the script. The perspectives have to be in the script, and you can tell if it works from there. It’s actually not so complicated with Toni Erdmann. We start the movie with him and then she takes it over because it becomes her story.

It’s interesting you say that it all has to be in the script, because the dynamic between the actors seems so significant.
That’s true, it is, and I cast the actors together with that in mind. Two actors together, sometimes it works, and sometimes it doesn’t. It’s also a question of how they approach a scene and if they can really play with each other.

How many actors did you work with before settling on these two?
I cast 20 actors for each role.

Yeah. I really wanted to be sure. I really found the pairing out because of the casting process: I wouldn’t have thought to put these two together without seeing them together during the casting. If the film is so much about the characters, you have to be sure that it’s really the right constellation. And once I’d cast Sandra and Peter, too, I went back to script and made some small adjustments to the characters, just to align them better.

This is incredibly specific, but did you know, before casting Sandra, that she’d have to sing “The Greatest Love of All”?
Yeah! That was in the script. I never had another song in mind: I found Whitney Houston perfect for the scene, and I had it in mind that the character would sing it in a very aggressive way.

Did you know Sandra could sing?
I knew that Sandra could sing. [Laughs] I’m sorry, Sandra just walked into the room. Yes, I knew she could sing, but I didn’t know she could sing so well. After we decided to work together, we went to one of these karaoke bars in Berlin—one of the little boxes you can go into and sing, and we tried out the song there.

It’s a hard song to sing.
It’s really hard! I tried it myself, and it was so embarrassing — it’s really tough, almost impossible. You have to try it.

Oh I have. I sang it at karaoke during the festival in honor of the film.
Ahh! Ha ha! Yes!

I wanted to ask about the Toni Erdmann costume. Did you always know it would be false teeth and a wig?
It depended. For every actor I looked to cast, I also had to find the right Toni, you know? With every actor Toni would have been different. We tried something like a hundred wigs. With Peter it worked so well with that long hair. It was really the worst wig—very old and damaged, that some makeup artist gave me for the casting. Really it looks so unbelievable and so unrealistic that I thought, I like it so much, but we cannot take it, it’s too much—it’ll be too jokey, it’ll kill the film. I tried to rebuild the wig, because I wanted the same thing but more realistic. So we started rehearsing with this realistic wig. Then on the first day of shooting, Sandra walked by, looked at Peter, and said, “Oh, I miss the old wig.” She was so right. So I asked the makeup artist if she could go and find the old wig again — and she said, “Oh, I already prepared it, here you go.”

So the wig is crucial.
It is. We thought very hard about the wig. It had to be believable that he made the costume himself, very fast. But on the other hand he had to be a certain type of Toni, with a certain funniness—he had to be a warm character, and not too freaky. We thought a long time about this stupid costume.

I assume it’ll be a popular Halloween costume.
Ah! That would be so funny! We will see.