Dr. K and Malik Return in 'This Is Us' Season 4 Finale Sneak Peek (PHOTOS)

Meaghan Darwish

This Is Us' Season 4 finale is nearly here, which means some major tension as the Pearson siblings and extended family convene for baby Jack's first birthday celebration.

In the episode titled "Strangers: Part Two," sibling contentions flare between Randall (Sterling K. Brown) and Kevin (Justin Hartley), likely due to the fact that Rebecca (Mandy Moore) agreed to participate in the clinical trial for her Alzheimer's despite her previous aversion. How will the family get-together conclude? Viewers will have to tune in to find out.

'This Is Us': Will the Clinical Trial Work? Why It May Not Help Rebecca

'This Is Us': Will the Clinical Trial Work? Why It May Not Help Rebecca

Rebecca's future has been teased various times throughout Season 4, could those flash forwards hold answers?

Until then, click through the gallery above for a sneak peek which teases the return of beloved Dr. K (Gerald McRaney), Malik (Asante Blackk) and Uncle Nicky (Griffin Dunne).

This Is Us, Tuesdays, 9/8c, NBC