'This Is Us' Fall Finale Reveals Twist About Jack's Brother Nicky's Fate

This Is Us left fans in shock with the reveal that a long believed dead member of the Pearson family might be alive during the final seconds of the season three finale.

With the trial period for Nicky (Michael Angarano) at Jack's (Milo Ventimiglia) about to run its course, he attempts to reach out to his drug-addicted brother by inviting him to an unspecified location.

Nicky lashes out at him and he ends up punching Nicky in the face.

"I got 48 hours left with yo kid, that's all, 48 hours and then you're back on your own base," Jack tells him before Nicky finally agrees to go with him.

In the present day, Kevin (Justin Hartley) begins to feel impatient on his and Zoe's (Melanie Liburd) trip to Vietnam to find answers.

Later, the show caught up with Jack and Nicky by the lake and he told his younger brother that their goal had to be to survive the war and stay on course so that when it was over, their time in Vietnam could be nothing but a distant memory.

"Our goal is to kill people," Nicky said, leaving Jack speechless. In the present, Kevin and Zoe arrive close to the village to meet with a local historian, who had experience wartime in Vietnam as a boy.

As Kevin arrived at the modern-day village where Jack was once stationed, he could feel closer to his father. In the past, Nicky wakes up in the middle of the night and attempts to quietly rummage through the supposed to find drugs. That morning, Jack wakes and notices that Nicky is not in his tent, he finds him high pretending to shoot the villagers with his fingers.

Jack says he will get him cleaned up, but Nicky tells him he doesn't want to do that.

"I see it all again when I'm clean," Nicky says. "I'm not going to complete the mission."

Kevin later talks to the historian about Vietnam and asks him if he recognizes Jack. He says no, and he also fails to identify the woman with the necklace. He recognizes Kevin as the Manny and seems distracted, then sharing a story about how his father would lie to them about what he was doing out of the village to not tell them what he was doing fighting against the Americans. With the story, the man tells Kevin that his fathers both hid their war secrets for them so that they could not be sharing a meal together in peace.

As Kevin and Zoe think about whether or not they are done with their mission for answers, Jack wonders where his brother is until he hears an explosion and Jack lunges into the water. In that moment Kevin finds out that Nicky is not listed in the war database as a casualty, meaning that if he is dead it did not happen in Vietnam.

The fall finale ends with the shadow of an elderly man sitting in what looks like a trailer, and the camera focuses on a piece of mail with the name Nicholas Pierson.

Looks like Jack Pearson's brother might still be alive, though that leaves the question as to why he is believed to be dead up in the air.

This Is Us will return with all new episodes Tuesday, Jan. 15 at 9 p.m. ET on NBC.