Warning: This article contains spoilers for True Detective: Night Country, episode 2, “Part 2.”

When True Detective: Night Country showrunner, director, and writer Issa López sat down to write what would become known as the “corpsicle” — the horrifying frozen mess of entangled bodies belonging to the missing Tsalal researchers — the filmmaker side of her brain was angry with the writer side.

“That’s the filmmaker’s problem when you have the writer’s cap on. So obviously when I sent it to the studio, they were like, ‘What are you thinking?’ And I said, ‘You’ll see.’ But I had no idea,” she recalls with a laugh. But she knew she had no choice but to figure it out. “Me as the filmmaker thought if we don’t manage to do this, I have to rewrite this, because if we fail with the corpsicle, there’s no series. It is so center. It’s the MacGuffin of the series,” she says.

Navarro (Kali Reis), Danvers (Jodie Foster), and Prior (Finn Bennett) stare at the corpsicle in ‘True Detective: Night Country’.Max

So, she started with a pretty gnarly mental image: a rat king. For those that aren’t familiar — don’t Google it, López warns — it’s essentially a bunch of rats whose tails have become entwined, forming a grotesque rodent mass. “It’s a rat king of people that they panic and they die because they’re knotted,” she explains of her corpsicle, the full extent of which is fully revealed in episode 2 after first being discovered at the tail end of the premiere.

The filmmaker also looked to Gustave Doré’s illustrations for Dante’s Inferno for inspiration, and took all of this to the production team and prosthetic makers. The fact that the dead scientists were frozen in ice was actually a help and not a hindrance, she says. “I used to explain it to my team and the prosthetic makers, ‘Think of shrimp frozen in a block. You don’t know how many shrimp are there in that block. So let’s think like that,'” she says.

From there, the team created models with little dolls to understand how the scientists were knotted and what their various expressions would be. “Each of their expressions had to be specific,” López says. “And for that I thought of Mexican mummified bodies. We have that in Mexico. And as a kid, I saw them and they were engraved in my mind. So those expressions of agony come from mummified bodies.”

Prior (Finn Bennett) and Danvers (Jodie Foster) investigate the corpsicle in ‘True Detective: Night Country’.Max

Prior (Finn Bennett) gets up close and personal with the corpsicle in ‘True Detective: Night Country’.Max

As for the name of the entity itself, López says she had called it that in the script from the beginning, but it wasn’t until deep into postproduction that she realized it was never actually stated in the series. “I was in the mixing room, and I said, ‘We should have a sound of the corpsicle,'” she recalls. “And my sound engineer turned to me, white-faced, and said, ‘You called it what?’ And I was like, ‘The corpsicle.’ And he said, ‘That’s not in the series.’ And I said, ‘Oh my God, you are right!'”

So, after the actor’s strike ended and way after shooting had wrapped, López called up leading lady Jodie Foster — “[Her character Liz Danvers] was the perfect character to call it so,” says the director — to record a couple of lines about the corpsicle to put into the final mix.

“And,” she concludes, “all of that came together, and voilá, corpsicle.”