'That's just a piece of the puzzle,' says Moore. 'A big piece,' adds Ventimiglia.

How Jack dies: This Is Us creator, stars on the premiere's devastating ending

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SPOILER ALERT: This story contains plot details about Jack’s death from Tuesday’s season 2 premiere of This Is Us, titled “A Father’s Advice.”

Well, now you know. Sort of. Hurts a lot, doesn’t it?

This Is Us made an emotionally supercharged return to the air after a six-month hiatus on Tuesday night. Rebecca (Mandy Moore) seized control of her fracturing relationship with Jack (Milo Ventimiglia) by rescuing him from a drinking vortex. Beth (Susan Kelechi Watson) surprisingly defused the tension with her adoption-obsessed husband, Randall (Sterling K. Brown) by telling him that they should adopt an older child who “no one else in the world is going to help.” Oh, and Kevin (Justin Hartley) and Toby (Chris Sullivan) argued over who should be looking out the most for Kate (Chrissy Metz), while she thought it should be herself. (She also had an encouraging/discouraging audition.)

But it was the final moments of the season 2 premiere of the NBC family drama that fans will truly be buzzing about. Because those moments took us to the time and seeming place of Jack’s death, heretofore only a mystery.

The sequence was preceded by a potent scene in which Rebecca tried to save their marriage, only to be rebuffed by his self-loathing efforts to try to tackle his alcoholism by himself, only to then open the door that he shut on her and order him to get in the car. Once in the vehicle, she assured him, “Everything is going to be fine. Jack, look at me… In a few months from now, everything will be back to normal.” That scene then segued into a moment presumably a few months from then, in which Rebecca was wearing a Steelers jersey, looking devastated, driving numbly, with apparently Jack’s possessions in a bag in the back seat (watch, keys, notebook). No, everything was clearly not fine. We saw a grieving 17-year-old Kate (Hannah Zeile) — who was holding a dog — alongside a broken-up Randall (Niles Fitch), and Miguel (Jon Huertas). Kate said, “We have to find Kevin,” and went off to break the bad news to her twin brother (Logan Shroyer), who was off in a make-out session, wearing a leg cast. Rebecca pulled up to the Pearsons’ mailbox, and as she let out of a horrible, heartbreaking wail, we panned back to something hideous: a just-burned down house, police tape cordoning it off, and a few fire officials still on the scene. End of show.

(We’ll give you a moment.)

Did Jack die in that fire? Did something else happen? What is the significance of those items in Rebecca’s back seat? Whose dog is that? Who’s with Randall? Why is Kevin in a cast? So many questions flood one’s brain center, but you just took a big step toward getting the biggest one answered — How does Jack die? — as creator Dan Fogelman promised. And as he said, the rest of the answer will take shape over the course of the season. (Cue: the next round of the waiting game.)

At the PEOPLE and EW viewing party for the season 2 premiere, Mandy Moore, Milo Ventimiglia, Sterling K. Brown, Chrissy Metz, Justin Hartley, Susan Kelechi Watson, and Chris Sullivan along with creator Dan Fogelman joined PEOPLE and EW editorial director Jess Cagle to break down the premiere, and, most notably, that whopper of an ending.

“You’ve seen a lot of pieces — this was always the plan for the Big Three,” said Fogelman. “We had talked about the fire and what happened from day 1 of starting. This has always been the plan. You’re seeing a lot of things that are going to reveal themselves over the course of the season… The writers have sat and analyzed every bit of minutiae. A lot of the little things are going to come into play over the course of this season. All the answers about how Jack died, it’s all going to happen this season.”

“We don’t know the full story,” cautioned Moore. “We’ll just say that. That’s just a piece of the puzzle.”

“A big piece,” added Ventimiglia. “This helps. It’s like a pressure valve released a little bit. But as Dan has always said, ‘With this answer there’s still a lot of questions.’ I think people are going to have pay attention over the course of this season, and each episode, and understand what our medium Big Three are experiencing and where they happen to be in the moments that are an influence to Jack’s death.”

Fogelman revealed that the moment of Rebecca sobbing at the burned-down house was actually her first take. (The scene was filmed a week and a half ago, to keep its contents under wraps.) “We built a replica of the house five hours away, we had code names for everything,” he explained. “Mandy came to set and they put her in the car and what you see is literally her first take. After all that planning, it was like 30 seconds and then we were done.”

Moore wants you to pay attention to some of the clues planted in that final sequence. “There were some clues I don’t know if people picked up on — Kate was holding a dog, Randall’s got a girlfriend, and Kevin has a broken leg,” she says. “These are all things that I think people are going to see sort of the origin of in the next couple of episodes, leading up to figuring out a bigger piece of the puzzle.”

In addressing the questions on everyone’s mind, Fogelman went down a jokey conspiratorial wormhole. “Did he die in the fire? Did he get out of the fire? But we’re not misdirecting — he didn’t die four years later. Did he start the fire? Did Toby start the fire?” When Sullivan interjected, “It was Miguel,” Fogelman laughed and said: “Sully is still convinced it’s Miguel — he won’t give up on it.”

As for other key moments in the episode, Moore talked about Rebecca deciding to re-open the door that Jack closed and taking charge of her relationship. “Finally I get to be somewhat heroic!” she quipped. “She takes on the role that Jack normally fills, which felt pretty good.”

Metz, meanwhile, found beauty in Kate standing up for herself and recognizing that she wasn’t good enough. Yet. “I think it’s nice to see a woman say, ‘You know what, I’m not great. I’m trying to figure it out and I will work at it’ — especially Kate,” she says. “Because she’s always felt as if she’s never good enough, and for her to take a step back and say, ‘You know what? I’m just going to have to work at it and sometimes that’s what it takes to follow what you love.’ So I think that’s really beautiful. And, of course, an amazing fiancé and an amazing brother who come to the aid and the rescue even though Kate told them not to.”

On the adoption-journey front, Brown saw Randall’s push to adopt as honoring his family legacy, specifically William’s. “He’s lost his biological father, but he wound up inadvertently doing something that changed the trajectory of my life,” said Brown. “So he’s passed away, it’s sort of like fulfilling the circle of life. One person passed away, it only feels right to bring someone else in to honor my parents who gave me a life. To be able to do that for someone else feels like the right thing to do. It also kind of puts Randall firmly in the moment instead of looking towards the future. He’s such a goal-oriented individual that he’s finally taking time to be here, to be with his children, to really relish the experience of the now.”

Added Watson: “What was most interesting for me is, it’s a way that you haven’t seen them before. Rarely are they on a different page for a long period of the time… Because they’re on two very different sides but is there somewhere in the middle they can meet, so I can make his dream work, and somehow it works for me as well and is this honoring William? And I learned that she actually wants to honor William too. It’s not just something that Randall wants to do. It means something to her to honor him as well and that was a surprise to me. I was like, Oh this isn’t just him, she wants to do something too. He’s had that effect on her as well.”

Meanwhile, Hartley gushed about the upcoming guest spot by Sylvester Stallone, who stars in the Ron Howard movie with Kevin. “He is the movie star, and he has this ability to sort of disarm everyone in the room, and somehow someway he walks into the room and when he starts talking you, he’s like a guy and then you’re able to start working,” said Hartley. “He’s a master at that. He comes in and makes everyone laugh. He gives a great performance, and then when he’s gone, you miss him.”

Of course, on This Is Us, no one is ever really gone.

To read a Q&A with creator Dan Fogelman about all the clues in that final sequence, click here.

(Additional reporting by Maureen Lenker)