Mandy Moore Teases This Is Us Season 3's Vietnam War Storyline: 'It's Really Powerful'

The mystery of how Jack Pearson died has finally been solved, but questions about how he became the man he was remain.

Season 3 of This Is Us premieres Tuesday and will explore Jack’s (Milo Ventimiglia) past as a soldier in the Vietnam War alongside his brother Nicky, who died in battle. And Mandy Moore — who plays Jack’s loving wife Rebecca — says it’s an especially powerful plot point.

“It’s hard to say stuff without giving anything away!” she told PEOPLE with a laugh while celebrating her fall cover of DuJour at TAO Downtown in Manhattan with founder of DuJour media, Jason Binn on Monday night. “Jack has a whole Vietnam storyline that I think is so fascinating and not often seen, something of this magnitude on network television.”

She adds: “It’s really powerful, and it gives us further evidence of who this man was, like what he brought to the table in his relationship, in his marriage, as a father. There’s a lot about that time in his life that nobody knows about that we’ll start to dig into this season, and I think it’s really interesting and compelling.”

RELATED VIDEO: This Is Us: Season 3 Primer

As for her off-screen partner, Moore is happily engaged to rocker Taylor Goldsmith, who proposed in September 2017.

“It’ll be intimate and quiet,” she said of their wedding ceremony, adding that a year after he popped the question, they’re still not deep into planning mode. “I mean, we’re starting to talk about it, but no real movement yet.”

This Is Us premieres Tuesday at 9 p.m. ET on NBC.

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