Henwick once walked off a set after a horrible all-nighter.

Jessica Henwickwas determined to never be an assistant again.

Until she had to play one in a film.

Jessica Henwick

Jessica Henwick.Kanya Iwana for EW

The actress, who began her career behind the camera, had plenty of personal experience to draw from.

I was like, I’m done.'"

“We finished the full day of work.

and the wedding was the next day and the tanks hadn’t come.

We were like, ‘We’ve got to blow up 2000 balloons manually.’

I did it the entire night and I pulled an all-nighter.”

“It got to 6:30 a.m.,” she remembers.

“And I had just finished and I was dying.

And an actor walked on the set and she was like, ‘Oh, my God, it’ssoearly.’

I literally went, ‘I quit.’

I walked off the film.”

Luckily for Henwick the experience came in handy while developing herGlass Onioncharacter.

“I tried to capture that feeling that I had that day,” she reflects.

“That’s how Peg feels every single day.

Just right on the verge of quitting.

‘Why am I doing this?’

But also she just can’t get out of it, because she loves and is reliant on Birdie.

It’s a very interesting, fascinating relationship.

We don’t get to see women in this relationship very often on screen.”

But that just gave her more room to play.

“She’s not written as someone who doesn’t like her job,” shetold EW previously.

It’s like a toxic, love-hate dynamic between the two of them.

Peg despises working for Birdie, but Birdie can’t live without her.

And Peg knows that.

And Peg loves her."

Oh, and those days as a P.A.

weren’t all bad Henwick once wroteGlass Onionwriter-directorRian Johnsona fan letter when she was still a film student.

How’s that for a little whodunnit kismet?

Glass Onion: A Knives Out Mysteryis now playing in theaters for a limited one-week engagement until Nov. 30.

It hits Netflix Dec. 23.