By Clark Collis
December 12, 2016 at 05:13 PM EST

In director André Øvredal’s new horror film The Autopsy of Jane Doe (out Dec. 21), Brian Cox and Emile Hirsch play father-and-son morticians trying to discover what killed a woman who is found buried at the site of a massacre. To prepare himself for the film, Hirsch arranged to spend time at the Los Angeles County Morgue. What was that like?

“It was my 30th birthday and I decided to celebrate by going to the Los Angeles County Morgue,” Hirsch says on this week’s episode of Sirius XM’s Entertainment Weirdly. “I signed some paperwork, so that if you get, like, Ebola or something, then you’re not going to sue them afterward. And I don’t have Ebola! We’re good. I went from never having seen a dead body ever before to literally seeing, like, 400 right away in this massive crypt where the bodies are all wrapped in plastic. Then I went into the autopsy room. They were like, ‘Come on in!’ They gave me a mask and I saw five or six active autopsies, all happening at once. This is one of the biggest morgues in the world. To say that it was shocking would be to put it so mildly. It was life-changing, in a way. It just rocks your idea of life. I remember I called the director afterward and I was like, ‘Man, if you can capture one-tenth of what I just experienced in there, this is going to be the most shocking movie ever.'”

Hear the full interview with Hirsch on Entertainment Weirdly Monday at 1 p.m. ET, and see the trailer for The Autopsy of Jane Doe below.