Randall’s anger at his brother hasn’t quite hit full boil in this exclusive sneak peak at tonight’s This Is Us (NBC, 9/8c) — but something’s definitely simmering between Rebecca’s sons.

As you’ll see in the video above, Randall sets up a video call with his siblings to discuss a new plan of attack for Rebecca’s recently diagnosed Alzheimer’s Disease. After so much research that he’s “halfway to medical school,” Randall strongly suggests that Mama Pearson enroll in a nine-month, seemingly in-patient clinical trial.

Oh, and it’s in St. Louis.

“I would like your help getting her on board,” Randall tells Kate and Kevin, who are surprised — to say the least — that he thinks uprooting Rebecca is the best choice right now. “You don’t think all of this is a little premature?” Kevin wonders, while Kate points out that their mom “just got a diagnosis.” But Randall presses on, and as he speaks, you can see Kevin growing less and less comfortable with the idea of moving Rebecca from her home in California.

“This is crazy, right?” Kev asks Kate. “This is nuts.” She points out that the decision ultimately is up to Rebecca, and Randall concurs — though you can start to feel the animosity we glimpsed during his initial visit with a therapist in the previous episode. What are the chances that this conversation is the start of the rift that causes Randall and Kevin to stop speaking by The Big Three’s 40th birthday?

Press PLAY on the video above to watch the tense call unfold, then hit the comments: Would you back Randall’s plan?