Big change is coming for the Big Three.
The final trilogy of "This Is Us" -- which will follow a different sibling in each episode -- begins March 15 on NBC. Starting with Kevin (Justin Hartley), followed by Kate (Chrissy Metz), and finishing with Randall (Sterling K. Brown), the episodes will highlight the decisions each sibling makes after Rebecca Pearson -- who is battling early onset Alzheimer's -- tells her children to take risks and that this disease shouldn't hold them back.
But ahead of what will no doubt be an emotional rollercoaster, Hartley teased what big changes will be coming for the Big Three.
"Each character is making a decision that is going to change the course of their life from here," the actor told Entertainment Weekly in an interview. "You're going to see the impact that had on the three kids and what they choose to do because of that very powerful speech."
Get Boston local news, weather forecasts, lifestyle and entertainment stories to your inbox. Sign up for NBC Boston’s newsletters.
"[They're] very clear about what she wanted -- until they go to do it," he continued. "And that's one of the things that happens in the episode: Kevin has this idea of what his mom wants, and he's on a mission, like, 'Okay, this is going to be my thing.'"
Hartley also noted that after a shocking, devastating event, Kevin "discovers a really beautiful part of himself through all of that tragedy. All three kids do that."
In the trilogy, which Hartley describes as "seminal," each character's decision will be "a defining moment--a line in the sand kind of thing."
"These characters that we've seen for the past six years are all of a sudden leading different lives," he explained, "which is kind of cool."
Now all we have to do is grab a box of tissues and tune in to "This Is Us" when it airs March 15 on NBC.
E! News and NBC are both part of the NBCUniversal family.