Mandy Moore & Milo Ventimiglia Reveal 'This Is Us' Season 4 Finale Secrets

Jim Halterman
Mandy Moore Milo Ventimiglia This Is Us Season 4
Preview Jeff Lipsky

Primetime's biggest tearjerker: It's a title This Is Us has held since its 2016 premiere, when Jack and Rebecca Pearson (Milo Ventimiglia and Mandy Moore) lost one of their triplets during birth and still left a Pittsburgh-area hospital with "The Big 3": son Kevin, his biological sister Kate and their later adopted brother Randall. Now in its fourth season, NBC's decade-hopping drama about the close-knit and at times dysfunctional family continues to churn out equally memorable twists week after week.

Some recent reveals have been heartwarming: Kevin (Justin Hartley) will soon have a pregnant fiancée! Others, like an aging Rebecca learning her mild cognitive impairment will lead to Alzheimer's, are heart-wrenching. "The way Rebecca is facing the future is so brave, and so stoic and graceful," Moore says. "Not letting my grief for her filter into the scenes is what I find most difficult. Sometimes I get back to my trailer and just weep."

'This Is Us' Mandy Moore & Milo Ventimiglia Open Up About Their TV Marriage (VIDEO)

'This Is Us' Mandy Moore & Milo Ventimiglia Open Up About Their TV Marriage (VIDEO)

The stars of NBC's biggest hit answered our burning Season 4 questions heading into the March 24 finale.

What should viewers brace for as the March 24 finale looms? And how does the show protect those revelations? Creator Dan Fogelman and the heads of the family, Ventimiglia and Moore, offer a preview.

Kevin and Randall's blowup will be brutal  

this is us kevin randall

(Credit: Will Hart/NBC)

In last November's Thanksgiving episode, a flash-forward to August 31, 2020, revealed Kevin and Randall (Sterling K. Brown) will no longer be speaking on the Pearson siblings' 40th birthday. The tension between the brothers has been building the entire series, Fogelman notes, but now, he says, "it's the biggest storyline in our remaining episodes."

While Fogelman is mum on the "scary and fraught" breaking point we see in the finale, the alpha males are already clashing over who's best qualified to manage Rebecca's care. Responsible Philadelphia city councilman Randall feels he's held the family together since Jack's 1998 death but recently began therapy for his lifelong anxiety at the insistence of wife Beth (Susan Kelechi Watson). Fun-loving famous actor Kevin has proven he can be an empathetic support system for his uncle Nicky (Griffin Dunne), a Vietnam vet and fellow recovering addict. Yet he still makes impulsive choices, like sleeping with troubled vet Cassidy (Jennifer Morrison) last October and, in January, Kate's (Chrissy Metz) best friend, Madison (Caitlin Thompson).

6 'This Is Us' Series Callbacks From 'The Cabin' Episode

6 'This Is Us' Series Callbacks From 'The Cabin' Episode

The latest episode included more than a few nods to past episodes.

March 17's Randall-centric episode is "as ambitious as anything we've attacked in terms of how we present Randall looking inward at himself," Fogelman says, adding that fan favorite Ron Cephas Jones — reprising his Emmy-winning role as Randall’s now-deceased biological dad, William Hill — plays "a gigantic part."

Before the season is out, other characters resurface "to propel us forward," Fogelman hints. (The drama has been renewed through Season 6.) He also promises we'll learn the identity of Kevin's fiancée, with popular theories ranging from either of the aforementioned dalliances (do the math!) to Kevin's ex-wife, Sophie (Alexandra Breckenridge), the one who keeps getting away. And Kate and her husband, Toby (Chris Sullivan) — back in a good place after a rocky patch following the birth of their blind son, Jack — are in for what Fogelman describes as "a shift that, I think, will catch people by surprise…"

Milo and Mandy break a cast record

This Is Us Season 4 mandy milo

(Credit: Ron Batzdorff/NBC)

Fans who swoon over Jack and Rebecca's romantic, hard-fought relationship that spanned the '70s, '80s and '90s should be pleased. On March 17, "Milo and Mandy play in more time periods in one episode than anyone has ever done," Fogelman wagers. 

Covering that amount of ground in an hour is a testament not only to the hair and makeup and wardrobe departments but also to the actors' bond. "We can always just share a simple look and know exactly where we're at," Ventimiglia says. Of course, they also put in a considerable amount of work, discussing scenes in advance, spontaneously running lines en route to set and focusing the young actors who portray the Big 3 as children. 

Justin Hartley on Directing 'This Is Us' & What's Next for Kevin This Season

Justin Hartley on Directing 'This Is Us' & What's Next for Kevin This Season

Hartley also talks family drama with the Big 3, learning from Ron Howard, and the Kevin-Madison relationship.

"Corralling" the 5-year-olds was Ventimiglia's greatest challenge this season, he admits with a laugh. "You just have to embrace and remember that they're kids," he says. "There are going to be moments where they'll want to stay in their chair and finish their cookie, and you have to just pick the chair up and fly them onto set and make sure they're laughing and smiling and you're grabbing the lines that you need."

In the season finale, look for Jack and Rebecca to "return to a place they haven't been in a while," Fogelman teases. And they'll celebrate the Big 3's first birthday in 1981. (Ventimiglia is a natural with the babies on set too. Recounts Moore, "He's telling me, 'This is how you change a diaper.' 'This is how you swaddle.'") 

Keeping the story secret is like a CIA operation

This Is Us Season 4 Mandy Milo

(Credit: Mitchell Haddad/NBC)

Fogelman concedes the hoopla surrounding Jack's death from a heart attack after a house fire — a mystery solved in Season 2, in a post–Super Bowl episode watched by 27 million viewers — made producers "a little nuts" about spoilers.

This is an abbreviated version of TV Guide Magazine's latest cover story. For more from our conversation with the cast of  This Is Us, pick up the issue, on newsstands now. 

This Is Us, Season 4 Finale, Tuesday, March 24, 9/8c, NBC