‘This Is Us’ finally told us how Jack died — Milo Ventimiglia and Mandy Moore help us cope

It was the script so shrouded in secrecy that it was printed on red paper — to prevent photocopies from being made — and handed to the cast in person.

Fittingly titled “Super Bowl Sunday,” the long-anticipated episode of NBC’s hit drama “This Is Us” finally provided the answer to the central mystery that has loomed over the show since its debut season: How did Jack Pearson, the beloved patriarch of the Pearson clan, die?

“We all know now,” Milo Ventimiglia, who plays Jack, said by phone after the episode aired. “’I’m happy the year and a half, or however long we’ve had to hold it, of silence of Jack’s death is done.”

In a separate call Monday morning, Mandy Moore, who plays matriarch Rebecca Pearson, said she’s relieved that this piece of the puzzle is finally out in the world.

“It frees us to continue telling this story of this family and the aftermath,” she said.

The groundwork had been laid when the current sophomore season premiered last fall and hinted that a fire took Jack’s life. The circumstances came into focus with the Jan. 23 episode, which showed a faulty slow cooker sparking flames in the Pearson home — giving weight to speculation that Jack, indeed, perished in a fire. But Sunday’s episode saw Jack walk away from the blaze after saving his family — and the dog … and photo albums … and a moon necklace — the night of Super Bowl Sunday, Jack’s favorite day — in 1998.

His death, instead, came later at the hospital after suffering cardiac arrest caused by smoke inhalation.

“It was kind of what was just always in my brain of what happened to them — from inception,” “This Is Us” creator Dan Fogelman said of Jack’s cause of death. “I thought as it related to Jack — he is the hinge for this family. I always thought it would be a fire. And after this big, heroic escape, he would have this small, quiet death. That was always in my head.”

The fire sequence, which was filmed about 90 minutes outside Los Angeles in Newhall Ranch, was shot over three days in December, with the whole exterior and top half of the Pearson home rebuilt. There were stunt coordinators, stunt doubles — atypical for a show like “This Is Us” — because, well, they were working with actual fire.

“Even though we were as safe as we could be away from it, there were moments where the booming force of this fire was real and it was right on the other side of the door from us,” Ventimiglia said. “It was pretty terrifying.”

Of course, being in the presence of a raging fire can also make the “acting” part slightly hard to focus on.

“There were moments where Glenn [Ficarra] and John [Requa], the directors of the episode, were like, ‘Mi, we have a hard time asking this, but can you actually slow down so we can make sure we capture you in this fire?,’” Ventimiglia recalled with a laugh. “I was like, ‘Got it, got it. I’m moving a little fast. It’s a little scary, guys.’”

Then there was the heart-wrenching moment in the hospital when Rebecca, jolted by the news that her husband had died in the short time she was gone from his room to make a phone call and visit the vending machine, saw her husband’s body.

Moore said she didn’t know Ventimiglia was going to be lying on the hospital bed when she filmed the scene.

“I was very quiet — I was sitting in one of the rooms on the hospital set and I had my headphones in and was in my own world,” Moore said. “Then they called me to shoot that particular scene to go into Jack’s room and I didn’t know he was going to be there that first take. It was startling, to say the least. It was very jarring. When I was just mentally prepared to go in and see an empty hospital bed and have to conjure up something from there, but to see Milo in it was just hard.”

High intensity stunts and emotional breakdowns aside, the episode also had the unique challenge of incorporating footage from Super Bowl LII into the episode. Producer Nick Pavonetti worked with his team on adding certain markers — from the pregame show, the kickoff and a big play from the first or second quarter — into the episode, Fogelman said. There were dry-run rehearsals last week to see how quickly they would be able to clip the footage and get it into the feed that went out to the country.

Next comes Tuesday’s episode.

“The episode that airs [Tuesday] is maybe more sad somehow than last night’s episode because it’s the reality of: This man is gone,” said Moore. “The patriarch of this family is gone, and this family has to figure out how they are going to move forward without the most incredible presence in each of their lives. It’s pretty heartbreaking.”

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yvonne.villarreal@latimes.com

Twitter: @villarrealy