John Krasinski was experiencing a roller coaster of emotions. While making introductions just minutes before screening his new horror movie—A Quiet Place, which Krasinski directed, co-wrote, and stars in—the actor was beaming with pride. Before long, he was getting emotional as he introduced his co-stars at New York City’s AMC Lincoln Square theater: deaf actress Millicent Simmonds, Noah Jupe, and Emily Blunt, who is also Krasinski’s wife.

“This is actually happening! Perfect, I just blacked out. I have no idea what I’m about to say,” Krasinski joked to a packed crowd that included Blake Lively, Ryan Reynolds, Justin Theroux, Stanley Tucci, and Rob Marshall, who just directed Blunt in Mary Poppins Returns.

“I can’t tell you how much this movie means to me. I love that people are saying it’s scary. But to me, it is all about family and the metaphor for what it takes to be a parent, and the extremes that you would go through to protect your kids,” he said—before adding that he knew his words might sound “insane” when juxtaposed against the still being projected onto the big screen, which showed Blunt looking distressed while sitting in a bathtub.

“You laugh now, but afterwards you’re going to be, ‘I get it man!’” Krasinski continued. “So I’m just preparing you.”

A Quiet Place—in theaters April 6—focuses on a couple (Krasinski and Blunt) and their young children (Simmonds and Jupe) trying to survive in post-apocalyptic world filled with mysterious creatures who hunt by sound; the slightest noise leads the monsters to violently attack. The film uses sign language—the daughter is deaf—and just about 90 lines of spoken dialogue, most of which is whispered, adding an extra layer of terror to an already suspenseful premise. Critics are unanimously praising Krasinski for crafting a smart, riveting, genre-bending tale in his third outing as a feature director, following the 2016 indie comedy The Hollars and the 2009 drama Brief Interviews With Hideous Men. A Quiet Place is not only Krasinski’s first studio picture—it’s also his first movie in which he co-stars with Blunt.

“The biggest benefit is the support system,” he told Vanity Fair on the red carpet about the advantages of working with his spouse. “I was emotional every day, and she would stay for the scene she wasn’t in. She would have incredible ideas and incredible notes on shooting script and on color performances. She’s just the most supportive person to have around.”

Blunt didn’t initially intend to appear in the film. Though she loved the story, she was slightly hesitant to make a movie with her husband of eight years.

“Before we started, it was terrifying. You don’t know what will happen, and if your two processes are going to work together,” said Blunt at the premiere. “Some people were like, ‘You’re going to be divorced by the end of it.’ But we quickly learned we work really well together. We discovered new sides to each other that go beyond us being a married couple. We never really saw each other in a professional day-to-day basis. It’s a totally different experience to share work and go home together. We were really in the thick of it together, and it’s brought us closer. He’s an incredible director—very collaborative, spontaneous, and assured.”

Before the film’s 36-day shoot last fall, Krasinski said he discussed every shot with Blunt over long dinner conversations. To maintain a balanced and respectful relationship on set, the two promised to be truthful with each other about their work styles.

“The key to [our collaboration], I said was, ‘Let’s be as honest with the movie as we are in our marriage, and let’s just talk about everything,’” Krasinski explained. “‘If there’s any problems you have or things you want to change, let’s talk about it now so we don’t do it on set.’ So we just went through all the intensity, walked through what it would be like, what she wanted to do and what I wanted her to do. She’s as good as it gets.”

Krasinski didn’t have to offer any notes to Blunt during the film’s most suspenseful moment, when Blunt’s character is sitting in a bathtub moments from giving birth. She must stay silent despite the excruciating pains of labor, or she’ll be killed by the monster that appears in the hallway just outside the bathroom.

“She’s the only one out of the two of us that’s exactly been through it. So my thing was let her do it,” he said with a smile. “No direction needed!”

And even now that he’s had experience being in charge, Krasinski isn’t planning to keep calling the shots.

“She’s always the boss, and I knew it,” he said. “In the manual, it says she’s the boss. So luckily, she let me direct, and then we came home—and then she went back to being the boss.”