By Marc Snetiker
Updated November 19, 2015 at 02:09 PM EST

Before you go see Julia Roberts writhing in a dumpster in the powerful crime thriller Secret in Their Eyes (in theaters on Nov. 20), just know this: the Oscar-winning actress had to do a lot of laughing before the crying.

“You have to have a sense of humor about it,” says the actress, who plays a district-attorney investigator forced to re-live the tragic case of her daughter’s murder 13 years prior. “There are times you go to work and you do all of this crazy dramatic stuff or we have guns and [an actor’s] on the ground bleeding, and I come home and [my son] Finn’s like, ‘Can we have meatloaf?’ It gives you such instant perspective.”

The pursuit of (fleeting) happiness started even before shooting began. Knowing she’d be spending time in the trenches with her frequent scene companion, Chiwetel Ejiofor (who plays her character’s former professional partner), Roberts, 48, made sure to find the time to establish a baseline of lightheartedness. “I had met Chiwetel just ever so briefly over the last year. We had done a photo shoot together — Chiwetel and Idris Elba and George Clooney and I. We spent an afternoon together and it was a fun day and so incredible to have at the beginning of shooting,” she recalls.

She continues: “Chiwetel and I would end up sitting [together] on set and the crew would be like, ‘Can you just move over a little bit? They’re setting this up.’ And we’d slowly get edged out of the entire space.”

Roberts laughs, as she is so wont to do. “We’d find ourselves sitting in the back of this bar in downtown L.A., telling stories. He makes me laugh so hard. It was so unexpected how absolutely hilarious he is. And he has such a great laugh. And for some reason — I don’t know, he’s such a great actor and he’s English and he stands up so straight — I just didn’t expect him to be someone who could belly laugh. It made me so happy and we had such a lovely time.”

Roberts maintains the giggly duo was “lucky” to find their joy early. “Even in the first read-through, somebody at one point did something funny and we all laughed and I said, ‘Enjoy it because that’s the end of it. This is the only fun day we’re ever going to have.’”

It wasn’t an off-base prediction. During the ensuing months of filming, Roberts would challenge herself with a role that demanded tragedy, despair, and steely resolve in almost equal measure. But she says the key to surviving any dramatic role — especially the pivotal, powerful one she portrays in Secret — is the ability to separate the laughs from the loss. “We all felt you don’t actually have to be miserable to be able to find the truth in the misery we were trying to relay,” she says.

While the film’s director Billy Ray says he (and most of the crew) took home Roberts’ performance, the actress was able to shake off Secret thanks to the presence of her husband, the film’s cinematographer, Danny Moder. “Danny and I often times went home together and had that time to talk about things, so by the time we got home, all we wanted to be was home,” she says. “We didn’t have that thing that we often do where you come home and you share with your spouse, Well, this is what we did today. We were able to go straight to home life.”

Secret in Their Eyes

  • Movie
  • PG-13
  • 111 minutes
  • Billy Ray