This Is Us Season 4 Premiere: Mandy Moore Teases 'Unexpected Twists' That She 'Didn't See Coming'

Mandy Moore knows the ending of This Is Us, but even she was shocked to learn what happens in season 4.

“There are a few unexpected twists in the information that we find out in episode one of this season that I didn’t see coming,” the actress tells PEOPLE.

The season 4 trailer left more questions than answers as many new faces will impact the Pearson household in past, present and future.

“It’s going to surprise people and it’s satisfying and it does change the game. It changes the world of the show in a way,” teases Moore, who earned her first Emmy nomination for her role as matriarch Rebecca Pearson.

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“Not that I know everything about the show, but you know we kind of have carte blanche to go in the writers’ room and ask questions. It’s sort of like Homeland in there,” she says. “There’s the dry erase board filled with information and they have like every single episode for the next like two seasons, I think, like sort of starting to be storyboarded out. Maybe not as much for season 5.”

Moore and costars Milo Ventimiglia, Chrissy Metz, Sterling K. Brown and Justin Hartley have learned about the trajectory of the remaining three seasons of the show from co-creator Dan Fogelman.

“I know the major bullet points of things that sort of happen along the line,” Moore says. “But I was even surprised by some of the twists that I was like, ‘Oh, okay. Didn’t see that coming or I didn’t know that this is when we were going to find out that piece of information.’ “

Season 3 of This Is Us foreshadowed many exciting life changes for Rebecca and the Big 3 with the flash-forward finale. But there were also some devastating twists, including the possible demise of Kate and Toby’s relationship as well as the impending death of eighty-something Rebecca.

Meanwhile, in the present day, Randall and Beth readjust their lives with their daughters to a new life in Philadelphia for their careers. And a newly single Kevin, who relapsed, looks to further his career with a new movie role.

Season 4 of This Is Us premieres on Sept. 24 at 9 p.m. ET/PT on NBC.