Matthew Gray Gubler is going to scare the hell out of you.

The beloved actor, who we usually see in front of the camera as Dr. Spencer Reid, steps behind the scenes this week as director.

And when it seems like a monster is killing people in a variety of cases, we may just be diving head first into the horror genre.

Having had the chance to screen Criminal Minds Season 10 Episode 21, I can tell you this is one of the scariest episodes in series history, so I was glad to jump on the phone with Gubler and grill him about making such a fright of an hour.

Let’s see what he had to say about some of the choices made, how he assured the audience of some serious shocks and how he coaxed a truly scary performance out of fellow cast member Thomas Gibson...

TV Fanatic: I know you’ve directed on the show before, but this one you definitely seemed to get to do some different stuff, right?

Matthew Gray Gubler: I think every one of them I really tried to make different, unique and special. This one, of course, is a little more unrelenting in its pursuit of terrorizing the audience. I feel like that’s really my wheelhouse as director. The whole episode, Breen [Frazier, who penned the episode] and I wanted to present in a way as a magic trick, where you think something is one way and then it turns out to be something else and having the rug pulled out from you continually. It was the beginning of the teaser to the very end. I think it’s a really powerful piece, and a lot of that had to do with the writing.

TVF: What were the challenges that you faced, because it’s easy to kind of overplay a lot of those horror scenes and make them come off almost campy which yours didn’t at all.

MGG: I’m a giant fan of the horror genre and the fantasy genre but to me the biggest challenge is restraint. I always had to do that with all the Criminal Minds episodes I’ve done. Sort of couching it in a reality where you’re then able to make the preposterous seem extra-frightening because it’s actually believable.

If anything, it’s making sure that, in the editing room, it’s diligently cutting the moments you want to see so that the audience is on the edge of their seat, unable to look away. It’s taking your beautiful shots, and it’s taking the things you’re proud of, and forcing yourself not to show all of them at once.

TVF: Is the case in the episode based on a real case of some kind?

MGG: You know, luckily it’s not. The history of it is accurate, in terms of the Satanic Panic, and the era, the mid-80s, when kids were blaming Satan and it all ended up to be debunked, but the history of it is true, but the case itself is not.

TVF: Who or what came up with that monster sound? Because, I have to say, I loved the sound of the monster.

MGG: Oh, that was me. Thank you. Thank you, thank you, thank you. I was spending, I’m not even kidding, an hour-and-a-half just perfecting that sound. I almost don’t want to give it away but I will. It was scripted that there was this unearthly growl that was coming from the dog and scaring people. I tried a lion. I tried a hog. I tried everything until finally realizing the spookiest thing is the sound of a macaw, a type of bird.

Very eerie, I think, on a primal level [and] it actually resonates with people and it was just sort of building that into a three-part structure and making sure that the three moments would appear, that I wanted them to feel the same but escalate in tension, so you didn’t know it was macaw.

TVF: So it’s an actual macaw, or is it somebody doing a macaw?

MGG: It’s a real macaw!

TVF: Oh, awesome. It was really creepy. I loved it. Okay.

MGG: Thank you. Oh, thank you.

TVF: Yeah. Now I know you are in the episode as well, not a ton, but you are in there. Is it a freaky thing for you? I keep saying freaky, it’s my word of the day after seeing this episode.

MGG: I like that. I like that word. A good word, appropriate for this episode.

TVF: When you direct yourself, are you a supportive director, or do you kind of berate yourself and say, “You’re not doing a good job,” and “Give me more,” like a hardcore director?

MGG: [laughs] Good question. It’s always a little bit of a challenge but I really have great confidence in my show as a director and that helps me potentially, weirdly, it’s easier for to act in the ones that I direct because I feel like I need to do my best at all points because I don’t want to waste time on having to do extra takes of myself.

It is a little bit of a tough thing directing yourself. It’s weird, in a lot of ways it’s very easy and in a lot of ways it’s kind of challenging. The only thing that’s a bummer about it is the director in me wants to watch the monitor but of course I’m in the scene so I can’t really do that but I have to kind of direct the scene from within.

TVF: There is a kid in the episode and I’m curious how it was working with a child as director?

MGG: Yeah, I love directing kids and a lot of my episodes have had them. I think I work very well with kids and animals. It’s great. Very exceptionally bright child, his name is Elliott Smith, truly a great talent and he had a lot of questions about the monster. But of course, kids can relate almost more so than adults to the idea of a monster being under your bed. So he understood everything and just did a great job.

TVF: I was really blown away by Mr. Gibson’s performance in the episode. I thought he did such a good job. Without spoiling what he goes through, can you talk about just working with him on this?

MGG: Thank you. I’ve been given a little bit of a good advantage directing because I have worked with him as a director and as an actor for a decade. I completely know how talented he is and what he’s capable of and we just speak a language. He’s like my brother. We speak the same language and we were both of the same objective - just telling the best story possible and I have great faith in him as an actor and he has great faith in me as a director and it could not have been more of a pleasure to work with him. Actually, it was a very unique ride for him.

TVF: Again, without spoiling too much, I got the feeling that we may see some of what happens in the episode carry into future episodes. Can you talk to that?

MGG: Thank you. Breen Frazier wrote this episode and the three total I’ve directed [and] he and I are very similar. The same type of storytelling that gets under your skin and haunts you and so with Criminal Minds the best way to do that is to have a somewhat open-ended episode and I’m not giving too much away, again, but we like leaving the lingering question that makes people think about what they’ve seen for a longer than if you just immediately wrap it up. Our last one that we worked together on had a very similar ending where you weren’t quite sure at the ending. I love doing that with any sort of directing.

TVF: Tell me what else you’re up to outside of the show. I know you just did something at Upright Citizens Brigade here in Los Angeles.

MGG: Oh, yeah. I’ve been doing a lot. Trying to stay really busy. I’m shooting a movie in June I’m really excited about, I’m acting in it. I’m doing a lot more comedy. Love doing the UCB stuff. Just having the time of my life, as always, trying to entertain people.

TVF: What exactly does a monologist do? [Gubler was the monologist in the most recent UCB show he appeared in.]

MGG: A monologist, they do this amazing improv show where they have a guest host come on stage and take recommendations of words from the audience. Then, once the audience says something, like ‘bubblegum,’ I have to tell like a four-minute story that happened to me that involved bubblegum or sort of a free associate and tell some stories and then a troupe of improvers act out the story. It’s really funny and really fun. I love everyone at UCB so much, and my heart widened in comedy so it’s so great to be a part of their thing over there.

Criminal Minds Season 10 airs Wednesdays at 9/8c on CBS. 

Jim Halterman is the West Coast Editor of TV Fanatic and the owner of JimHalterman.com. Follow him on Twitter.