One of the biggest This Is Us secrets throughout Season 1 was the fact that Rebecca had kept in touch with Randall’s biological father, William (Ron Cephas Jones), despite the fact she told him she didn’t know who he was.
In the very emotional flashback video, Randall (Sterling K. Brown) finally confronts his mother about the secret during Thanksgiving dinner, blindsiding Rebecca (Mandy Moore).
“I went to William’s apartment to get his old Thanksgiving tapes. I was about to go and I saw this envelope and I said, ‘I know this handwriting, this is my mother’s handwriting,’” he emotionally tells her. Watch the clip above to see how the intense scene goes down.