|"Arthur and the Whole Truth"|
|Number in season:||1B|
|Original Airdate:|| October 10, 2016|
November 13, 2018 
|Written by:||Peter K. Hirsch|
|Storyboard by:||Jeremy O'Neill|
"Buster's Second Chance"
"Fern's Flights of Fancy"
Arthur finds out Buster has been lying to protect his feelings.
Arthur plays the piano in preparation for a recital. His father encourages him, but Arthur thinks he is getting worse and wishes people would tell him the truth. D.W. follows Arthur around and starts nagging him. Arthur admits that "sometimes, the truth can be a real pain" and is about to go to sleep, being interrupted by D.W. one last time.
Arthur shows Buster his caveman diorama. Buster shows Arthur his sabertooth tiger sculpted out of marzipan, leading Arthur to fear that his diorama is lame. Buster reassures him that he likes it.
Arthur gets a C+ on his diorama. Francine insults it and Buster gets a better grade. Francine says that Buster always tells Arthur what he thinks he wants to hear. In a baseball game, Buster says that Arthur was safe, and Francine again says that Buster did not genuinely think so.
Arthur looks at his diorama again and thinks that it is terrible. He imagines him and Buster in caveman times, and Arthur makes a spear. Buster says that the spear is great, and Arthur fails to hunt a woolly mammoth with it. When the mammoth almost gets in their cave, Buster admits that the spear is terrible but did not want Arthur to feel bad. Arthur throws his diorama away.
Arthur wears a shirt that uncle Fred gave him and asks Buster what he thinks of it. Everyone is repulsed, while Buster compliments it. Arthur gets mad at Buster, who then admits that he was lying and that he does not like the shirt. Arthur tells Buster that he can be honest, as Buster previously lied just to avoid arguing.
Arthur invites Buster to play Dark Bunny VI: Curse of the Moomy, although he admits that he does not like the game. Buster returns Arthur his Scare-Your-Pants-Off Club book, and they argue over whether the ending was good or not.
Arthur attends his recital, and Francine compliments his playing. Arthur says that he was nervous and hoped that he did not make a single mistake. Buster tells Arthur that he actually did make a mistake, having played a wrong note, but that the rest of the recital was amazing; Arthur gets offended, tells Buster that he was being mean, and asks his parents what they thought. D.W. picks up on the same mistake as Buster, and Arthur realizes that he was wrong.
Arthur goes to Buster to apologize. He admits that Buster was being honest and telling the truth, and that he should not have gotten angry. Buster gives Arthur an edible piano made of marzipan, and asks Arthur what he thinks of it. Arthur answers, "Trust me, you don't want to know!"
- Molly MacDonald
- George Lundgren
- Jane Read
- The Brain
- Binky Barnes
- Maria Pappas
- Muffy Crosswire
- Bitzi Baxter
- Arthur's shirt from Uncle Fred depicts Tex Hotel, that was originally seen during Buster's imagination sequence in "Bitzi's Beau" in Season 5.