The This Is Us Season 4 Trailer Left Us With Goosebumps . . . and a Lot of Questions

"You don't know us." That's the tagline for This Is Us season four, and it couldn't feel more accurate after watching the show's latest trailer. As Rebecca Pearson (Mandy Moore) delivers a heartfelt monologue, new characters and storylines flash across the screen, interspersed with clips of familiar faces. So . . who are these newcomers?

Fans might be surprised that the Big 3 aren't in the spotlight during the trailer, but the cast have been teasing an expansion for quite some time now. Last month, Chrissy Metz told Andy Cohen on Watch What Happens Live that, "We're going to meet some new characters, which is exciting, and we're going to see how they're all intertwined and how they all affect the Pearsons." We can always count on this show to keep us on our toes, and we're eagerly awaiting the extended premiere on Sept. 24.