Next month, executive producer Ryan Murphy will unveil Fox’s “Scream Queens,” the first of three series he’s currently working on — along with FX’s “American Horror Story: Hotel” and “American Crime Story: The People vs. O.J. Simpson.”

The comedy/horror series — which includes a star-studded cast headlined by Jamie Lee Curtis and Emma Roberts — follows a group of sorority sisters plagued by a devil-suited killer who’s picking off a victim, week by week.

Here, he tells Variety about building the cast, unmasking the killer — and who’ll be back next season.

Talk about casting Jamie Lee Curtis. Was it really Jamie or nothing?

It really was. I made that clear to (Fox CEOs) Dana (Walden) and Gary (Newman)… When she came in to meet, in typical Jamie Lee Curtis fashion, she brought photography books. She’s the queen of the book. She’s always sending everybody books as presents. She came in with a John Carpenter book for Brad and me, because she knew that we loved “Halloween” so much. Every fall I can’t wait till Halloween comes, because I love to turn on AMC and literally watch all the “Halloweens” that they air back to back. I’ll stay up till 4AM watching them. She tells great stories about the second one, and the worst wig of all time that she had to wear. What I love about her is that she’s very embracing of her place in the world. She has great respect for the filmmakers that she worked with and the fans. She gets that that genre is an artistic art form. She thinks it’s important, even though I think she doesn’t watch horror movies herself. She’s had such an amazing career. She’s from Hollywood royalty, so her stories date back to the ’40s. She talks about her mom and Hitchcock. She’s everything that you would want her to be. Everything about her, she didn’t disappoint. I feel like I made a really good friend in the process.

How much were you able to write to her?

That was the great thing about the casting. Almost all of those parts were created for those actors. We want Jamie Lee Curtis to kick ass, and tell these girls that they’re horrible little monsters. We want Jamie Lee Curtis to talk about what it was like in the 70’s and 80’s, fighting for feminism. Emma (Roberts’) part was written for her. I adore her and we worked with her in “Horror Story.” She kept saying, “I want to be snarky again. I loved it when I was bitchy.” Lea (Michele), I wanted her to do something completely wacky and fun after everything she had been through.

Was it hard to convince her to go makeup-free and wear a neck brace?

No. I called her up and I said, “I’ve got two words for you. Neck brace.” She said, “I’m in.” It was literally that simple. She wanted to do it. Of course, her character has an evolution, so I told her where she would start and where she would finish. She loved that.

Does anyone get to improv at all?

Nasim Pedrad was one of the last people cast. It was a very hard part to cast. We really didn’t know what we wanted to do. That part, it wasn’t written for anybody. She’s a total scene-stealer. If you’re going to work with somebody that’s an improv genius from “Saturday Night Live,” you got to let them run. We let her improv all the time, and half the stuff that’s in the show is stuff she just says. The joke is how to do a scene within a scene and not ruin the take by laughing because she’s so funny. It’ll be revealed why she’s stuck in the early 90’s. It’s a plot point which I love.

Is the show going to be victim of the week?

That’s part of the show. Jessica Lange used to always say that, too: “Why do people have to die?” Because it’s a horror show. I look at it as a horror show, but also like a Agatha Christie whodunnit, like “10 Little Indians,” which I was obsessed with as a kid. One by one, they’re getting picked off, and it’s an active search to find the killer. That definitely is part of the storytelling. We just did an episode where three people get offed by the devil killer. Some weeks, maybe one will or nobody will die. By the end of the season, very few of them will remain. In horror, there’s the tradition of the last girl. Usually, it’s the girl left standing, like Jamie Lee Curtis in “Halloween” or the “Friday the 13th” movies. We’re doing our version of that. There will be 4 or 5 of them that will go on, hopefully in success, next season to a different setting. Not a sorority. They’ll still be playing the same characters. They’ll be battling a new monster. Every season will be a new villain.

The actors don’t know who the killer is and who survives?

They don’t. They’ve been blackmailing me, bribing me, writing me. They all have their theories about who they think it is, and none of them have been right, which makes me very happy. I love their enthusiasm, because I feel, hopefully, that the audience will share it. When we were directing the first two episodes, Brad and I would always, for the most part, give those actors a take and say, “Pretend you’re the killer.” In the pilot, it’s very clear to me who is the killer. When the killer’s unmasked at the end, you’ll be able to go and be like, “Oh, yeah” and link all that stuff together.

So who will be back next year?

With success in “Scream Queens,” we’re going to have a big group of people that you’ve grown to know and love, but there will be exciting new additions who will come in. Like this year on “Horror Story” with Lady Gaga, who would’ve thought it? I never would’ve, this time last year, never. That’s the fun of it, that there’s always that possibility of some great person coming to you and saying, “I want to do that show.” That’s already happened with “Scream Queens.” People have called me and been like, “In the second year I want to do that show.”

Who has called?

I can’t say because I might cast them. I don’t want people to be mad, but I literally just did that with Max Greenfield, who I’ve loved since God was a boy and I said, “I know you’re a regular on this other show but if I write you three episodes will you do it?” He’s like, “Hell, yeah!” He had the time of his life. I love that.

How much should we read into the flashback scene at the beginning? 

That’s part of the mystery: Who is the baby in the bath water? Did that baby grow up to be one of our people? The mystery of the girl dying in the bathtub and the baby is played out through the whole season. Skyler, who plays Grace — her character is convinced she is the baby. Convinced. She’s trying to solve that mystery, because she feels like if she can figure out if she’s the baby, there is some link to the killer being connected to that crime at the beginning. In the second episode and third episode, it’s established that Jamie Lee’s character was involved in it, too. It’s all an interwoven mystery.

You’ve said you got pushback from the standards-and-practices department. What did they complain about?

For example, we researched how do sororities haze? What do they do, what are they doing right now? One of the things we came up was the poo-belly mayonnaise shot challenge, which you’ll see in the second episode. It’s awful. They force the pledges to strip down to their bra and panties, and they take a marker and write on their bodies where they need to be skinnier, and then they make them take mayonnaise shots. So some of the language that they wrote on the bodies was historically true, but that was a problem. We also found the vodka tampon challenge, where they put the tampons in vodka and then insert them. It’s an easy quick way to get drunk, and it can also lead to instant death, and it has. You can’t believe this s–t exists. So we were trying to write that. Sometimes you win and sometimes you lose, but I do feel that the show is brave in that way. I am proud of that. That stuff is there for a reason. It’s not just there to titillate.