Next Week's 'This Is Us' Promo Finally Gives Fans A Look At Jack & Nicky In Vietnam

It's time to see how "Jack became Jack." This Is Us viewers have watched Jack Pearson struggle with his own upbringing, fall in love with Rebecca, and be a model father. Now they'll get a chance to look at what truly took place while he was in Vietnam. As the This Is Us Season 3, Episode 4 promo teases, next week's installment of everyone's favorite TV cryfest will be devoted to the Pearson patriarch's days at war. The hour is being hailed as one that "simply can't be missed," so prepare to tune in and let those emotions loose.

"He's my little brother. It's my job to take care of him. That is my only job," Jack declares in the promo. This Is Us previously revealed that Jack had a secret sibling named Nicky, who supposedly died in Vietnam. In this week's episode, Jack's dad even made a callous remark about how Jack didn't look out for his brother. It appears a lot of the mystery surrounding Nicky's tragic fate will be resolved soon. New theories floating around suggest he could still be alive, but whatever the entire story actually is — it doesn't look like an easy one to digest. The promo also shows a bloodied Jack holding a fellow soldier who appears to be injured and in distress.

Even casual This Is Us viewers likely had a hunch that Jack's Vietnam history would be at the center of Season 3. Kevin's newfound curiousity about his dad increased on this week's episode when NPR's Terry Gross questioned him about the experience. Sadly, he realized he knew nothing about his pop's possible combat past and decided to go all in on digging up intel with the help of documentarian Zoe. Kevin even ultimately gets in touch with Mr. Robinson, a man who potentially served alongside Jack. Through Kevin's journey of exploration, it seems audiences will finally gain further insight on Jack's pre-Big Three and Rebecca life.

“We’re trying to really break some barriers for network television, in terms of creating something that’s so period, and so overseas,” co-showrunner Isaac Aptaker explained to Vulture in August about This Is Us' depiction of Vietnam. “It’s a real timeline that we’re going to live in and devote some serious episodes to. So it’s going to be a very fully real-life world. It’s not just little moments.”

The illuminating flashbacks that appear in Season 3, Episode 4 look like they're going to kick off that recurring arc.

"A lot of the heaviness and the sort of angst and burden that Jack carries around him throughout his life is very much connected to that line [his father's comment] and what happened to his brother, and we’re going to start exploring that next week," Aptaker explained to EW on what to expect.

While the pieces of the puzzle about Jack's death came together last season, there's still so much about him that This Is Us fans — and his own family — don't know. Even though it will probably require an industrial box of tissues, I think everyone's more than ready to learn the truth.