How scary is first-time filmmaker Ari Aster’s horror movie Hereditary? Well, cast member Alex Wolff was unnerved just reading Aster’s script. “My mother walked into my bedroom and I screamed out loud,” he tells EW. “I remember having a lot of trouble trying to sleep that night.”

Wolff, Toni Collette, Gabriel Byrne, and Milly Shapiro play members of a family attempting to recover from the death of their matriarch. It is not a huge spoiler to say that recovery never fully occurs as they’re hit by a series of traumatic events, which may have their origins in the family’s own twisted, mysterious history. “I guess the story reveals everything she’s ever wanted to know,” says Collette of her character. “But it happens in a way that she wasn’t expecting and does not enjoy. The scariest thing about it is, most films have a sense of hope, and there is no sense of hope in this. It’s just impending doom!”

Collette, seen below in an exclusive image from the June 8 release, says the experience of shooting Hereditary reminded her of making a certain M. Night Shyamalan’s supernatural box-office sensation. “On The Sixth Sense, there was some definite feeling we all had that it was going to somehow be special,” she recalls. “And it did actually come to pass that the film did really well and has been loved by a lot of people. Similarly, on Hereditary, I have been reluctant to say it, but there was a similar sense of something special. It was coming from some serious sh—, and deep focus, and hard f—ing work. It did definitely have a sense of being somehow — it’s going to sound like I’m up myself — but important to cinema.”

Image zoom Reid Chavis/A24

Hereditary was widely acclaimed as the most terrifying film shown at this year’s Sundance Film Festival and, according to Wolff, received a similarly warm reception when it played at SXSW — well, maybe warm isn’t quite the right word. “People flipped out at that screening,” says the actor. “People were crying and screaming. I was like, ‘Yes. ”