This Is Us star Chrissy Metz warns 'the wound gets opened' in ominous Kate-Toby episode

Kevin had his lightbulb moment in the first trilogy episode. What might happen when Kate has hers in the second installment? Will it mean lights out for her marriage to Toby?

That is the question looming over "The Hill," the next installment in the final trilogy showcase in the final season of This Is Us, which airs Tuesday night on NBC. Kate (Chrissy Metz), twin sister of Kevin (Justin Hartley), heads to San Francisco to reconnect with husband Toby (Chris Sullivan) and see how he's been long-distance living, with Rebecca's (Mandy Moore) inspirational Thanksgiving speech to pursue life to the fullest and take big chances resonating in her head.

"She's always taking her mom's words to heart," says Metz of Kate. "But I think it hits home and it rings in a different way than it ever has before. She really heard those words, and she started to really think and contemplate and begin this introspection of: 'What does make me happy and how do I get to that place?' What will it mean for the relationship, for her life? How does she set up her life in which she's truly happy? Because she's been on a hunt for real happiness for quite some time."

Kate and Toby's marriage has been shaky for a while, and given last season's flash-forward that revealed that Kate will marry Philip (Chris Geere), viewers know where this is all headed: Divorce. While this episode may not be the day that the trolley car officially arrives at Splitsville — as viewers also know, that will somehow involve a Big Green Egg — this week's installment will reveal the depth of their divide.

"It's a huge download of an episode and a huge awakening for both of them," says Metz, who co-wrote the episode. "People are in your life for a reason, a season, a lifetime, and sometimes the dynamics change and shift, and you grow out of people and if you don't grow together, you grow apart. And I feel that with this episode in particular, Kate and Toby are having a really hard look at: What does the relationship look like if he's happy somewhere else and she's happy somewhere else? That begins a conversation — a very, very tough conversation — and a very hard pill to swallow."

During this Bay Area adventure — which, by the way, was directed by Moore — Kate is attempting to roll with the changes in Toby's life while clinging to the Toby whom she fell in love with when they first met in season 1. (As you saw in the teaser for the episode, we mean that somewhat literally.)

"They're both excited and anxious for this time alone, but they also haven't spent much time alone together in quite some time and they're changing as people," hints Metz. "What you come to find out is Kate is really surviving the weekend by imagining having old Toby, the original Toby, with her."

In short, this weekend will have significant repercussions for the couple. "This is really the catalyst to the rest of not only the season, but the demise of their relationship essentially," she says. "It's really where the wound gets opened."

Bring some Band-Aids along with the Kleenex.

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