The cat’s out of the bag on “This is Us.”

During Season 1, episode 8, Randall finally learned the truth about the long standing agreement between his adoptive mother and birth father. During an earlier episode of the NBC drama, viewers learned that Rebecca had paid William a visit shortly after adopting her son, but this information did not trickle down to Randall until his wife accidentally found out.

“This is Us” will explore that relationship even further in Season 1, episode 9. According to TV Guide, the episode is going to center on a letter Rebecca (Mandy Moore) sent William (Ron Cephas Jones) with a photo of his son in it. This apparently served as the catalyst to their first meeting. “This is Us” fans will also see a second secret face-to-face between the duo, which the publication claims is even more tragic than the first. Her motives for keeping her meetings with William a secret will finally come to the surface, though it’s unclear whether viewers will be left feeling anymore satisfied after learning the truth.

“This is Us” Randall How will things change on “This is Us” now that Randall (Sterling K. Brown) knows the truth about his birth father and adoptive mother’s relationship? Photo: NBC

The episode prior served as something of a “This is Us” Thanksgiving special. During the episode Beth (Susan Kelechi Watson) and Randall (Sterling K. Brown) were preparing to host their own Thanksgiving. Viewers were treated to a flashback, which featured Randall’s racist grandparents, an itchy sweater and a caricature of a pilgrim. The entire family was invited to Randall and Beth’s, though it was clear Kev (Justin Hartley) could have done without Miguel (Jon Huertas). It also became evident that there was tension between Beth and Rebecca, who had been dodging her daughter-in-law’s phone calls.

Beth cornered Rebecca and told her once and for all that one of them has to tell Randall the truth. Rebecca plead with her to save it for another day, but Beth was not willing to budge. Before either could share the information with Randall, he slipped out of the house to pick something up from William’s apartment in Philadelphia for fear this will be his last Thanksgiving. While searching for recordings William and friends made in years prior, Randall came across a letter from Rebecca to William. His world was instantly shattered, but he returned home and attempted to keep the truth to himself.

The family carried out their yearly tradition of passing a ball of yarn and saying the many things they’re thankful for. When it was Randall’s turn, he finally caved and brought up the letter and photo to Rebecca. He burst into tears, questioning her decision to keep this information from him and left the table.

“This is Us” fans will recall in episode 3 that Rebecca met with William in the hopes that he’d be able to share information about himself and the child that would help them bond. William gave her a book of poems — written by the author whose poem William and Beth bonded over after eating a tray of special brownies in Season 1, episode 7 — which prompted her to change his name from Kyle to Randall. Rebecca and William came face-to-face for the first time in years shortly after Randall invited him to stay with he and Beth. She warned him not to hurt her son or reveal the truth about their relationship, unaware of what was to come.

“This is Us” airs Tuesday at 9 p.m. EST on NBC.