'This Is Us': Chrissy Metz, Mandy Moore and Chris Sullivan Tease Groundbreaking Episode (Exclusive)

Metz, Moore, Justin Hartley and Sterling K. Brown dish to ET on the questions they're excited for fans to get answers to.

This Is Us is adding a new perspective in Tuesday's episode, telling part of its story from baby Jack's point of view.

The cast of NBC's outgoing drama previewed the latest installment, which parallels Rebecca and Miguel's 10-year wedding anniversary in the present day to Rebecca and Jack's 10-year celebration in the past. Strewn throughout is the gradual implosion of Kate and Toby's marriage in the present, which comes to a head in the hour. And by focusing a significant portion of the episode through the eyes (and senses) of baby Jack -- who was born visually impaired -- the episode, titled "Saturday in the Park," is unlike any other.

"[Creator] Dan Fogelman is an innovator in modern television so I was not surprised," Chris Sullivan told ET's Denny Directo at This Is Us' opening night celebration at PaleyFest on Saturday at the Dolby Theatre. "Episode 11 has a lot of the world from Jack's perspective, which is mostly blind. And it's really clarifying as to what the world might be like or what it might be like to experience the world in that way."

"How beautiful," added Chrissy Metz. "How many times do we get to see a visually impaired actor, especially at his age and seeing from his point of view in such a beautiful, poetic way? But also such a heartbreaking way?"

The actress marveled over the young actor who plays baby Jack. "He's just the cutest little muffin. I can't even take it. My boyfriend and I were like, 'We can't watch it, it's just too much.' It's just wonderful... Listen, he's probably too smart for me. I'm not kidding, he's one of the smartest humans I've ever met."

The episode also introduces a new side of Rebecca that viewers still haven't really seen. For Mandy Moore, it was a real treat to get to dig into a lighter side to the character she's played from young adulthood to her 70s.

Ron Batzdorff/NBC

"It was fun, yeah," Moore hinted of the new shade she got to play opposite her onscreen husband played by Milo Ventimiglia. "We've been living in present day and a little bit of the future so much, to be able to go back to the past a little and not be in age makeup was a real delight." 

Moore also opened up about exploring Rebecca and Miguel's relationship on a deeper level this season. "I love that we're finally getting to see Rebecca and Miguel's love story unfold," she shared. "I mean, everyone deserves to have a second chance at love, a second chapter -- and that's exactly what this is." 

With the series beginning to wind down -- only seven more episodes await after Tuesday's episode, including the milestone 100th -- the cast revealed the series-long mysteries they're excited for fans to finally get the answers to.

"Where is Kate at the end? Where is she? I'm excited for people to discover that," Moore teased.

Metz agreed, echoing her co-star's sentiments: "Where is Kate? Where is she? I think we'll get an answer... She's somewhere."

Added Justin Hartley: "I think everyone wants to know the Toby-Kate situation. Everyone is really interested to know, at least I know I am, how far his career goes and how it affects his relationship with his kids and all of that. And hopefully people are interested in finding out who Kevin [ends up with]."

"He is ready. Your episode directed by Milo [Ventimiglia] was such a beautiful [one]," Sterling K. Brown praised. "You see him step into grown manhood, and not like it was forced upon him. He's like, 'No, this is something that I want for myself,' and now to find him be able to see him share his life with someone, I'm very excited to see that."

This Is Us airs Tuesdays at 9 p.m. ET/PT on NBC.

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