What's happening on This Is Us right now is an emotional roller coaster, even by This Is Us standards. (Consider this your spoiler warning.) Kate and Toby welcomed a baby boy, Jack, but he's premature and facing health problems. Kevin relapsed and just had an interesting encounter with his engaged ex-girlfriend, Sophie. (Stay tuned to see whether he mentions the latter to his current GF, Zoe.) Meanwhile, Randall and Beth had a major fight, and we still have Jack's very-much-alive brother, Nicky, to think about. It's hard to imagine how This Is Us creator Dan Fogelman will tie everything up in the season-three finale, but he has a plan—and it's going to shock you.

"It feels very big," Fogelman tells Glamour. "It feels like a real midpoint for us, and I’m very excited about it. The last five minutes of it are as big and sprawling and epic as we get."

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So what's in store? Fogelman is keeping specifics locked down, but he did reveal a few tidbits to us. He says Sophie doesn't appear in the season finale, so those hoping for a resolution about her coffee date with Kevin will have to wait. "I think there’s more to explore there between the two of them," Fogelman says. As for next season, "You never know. It depends on what happens."

Fogelman also revealed the finale dives "heavily back into the future," so expect to learn more about Much Older Rebecca. Remember, we found out in the midseason finale that Rebecca is the "her" Randall and Tess visit in the flash-forward, but we don't know anything beyond that. Thankfully, more information is coming. "I think people will have some questions pertaining to the ‘her’ storyline answered, but there will be other questions posed that you do not see coming," Mandy Moore (Rebecca) says.

Moore wasn't surprised when she found out what happens to her character in the future. "My reaction was, 'Oh, Rebecca,'" she says. "Dan Fogelman is a genius. I was like, 'Yeah. OK. I see that. I believe that. I understand that. Yep.'" Much Older Rebecca's exact ailment is still a mystery, and it probably won't be revealed in the season finale. (Moore wouldn't confirm or deny.) But she did debunk one fan theory: It's not Alzheimer's disease. "I love how people are sleuths," she says of the fan speculation that Rebecca has Alzheimer's. "I love that! That's a good theory. Not true, but I like it."