Arthur and Francine are paired up by Mr. Ratburn to do a report about the hero or heroine of their choice. Francine is already mad at Arthur for his making fun of a weird sweater she was wearing one day (calling her a "marshmallow"). But when they do research for their report in the library, they do not hear that it's closing and so they get locked in, and have to quickly settle their differences so they can get out.
Locked in the Library! contains examples of:
- Apology Gift: Realizing she was holding a dumb grudge for nothing when Arthur frantically searches for Francine after hearing a scream, Francine reveals she saved him a slice of pizza in the employees' lounge.
- Anger Born of Worry: D.W. is furious with her older brother and Francine after they were gone for hours. Aw, she does care.
- Angry Item Tapping: After Arthur receives a threatening note from Francine for calling her a marshmallow, he and Buster see the girls with angry looks on their faces. Muffy can be seen tapping a ruler on her desk.
- Bait-and-Switch: When Muffy presents her project, Mr. Ratburn asks Buster if he has anything to add. Buster walks to the front of the class, clears his throat, and says... "No." He then sits back down.
- Bittersweet Ending: While Arthur and Francine did escape the library, they still have to finish their homework assignment soon. Mr. Ratburn gives them an extension, saying he appreciates that they learned something. Francine and Arthur reconcile since they realized the "marshmallow" insult was small in the long run, especially since he ran to her rescue when he thought she was in danger. Even so, she still splatters him by accident when riding his bike.
- Book Ends: The short starts and ends with Francine splashing Arthur by accident while riding her bike.
- Both Sides Have a Point: Arthur is right that calling Francine a marshmallow due to her sweater is a pretty tiny insult in the grand scheme of things, which Francine even concedes by the end of the episode. He still refuses to apologize for it even though it still hurt Francine's feelings, which caused Francine to dig her heels in and make everything worse.
- Early-Installment Weirdness: Francine being a big Jerkass compared to subsequent seasons, of course.
- Explain, Explain... Oh, Crap!: As Arthur and Francine are locked in the library, they try to escape through the windows, but they fail, upon which, Arthur realizes something important...Arthur: I just remembered something.
Francine: What?!
Arthur: Today's Saturday, which means... the library is closed until...
[Francine gasps in horror]
Both: MONDAY!!! [echoes] - Growling Gut: Arthur's stomach lets out a hungry rumble once he and Francine realize that the library will be closed until Monday, meaning that they can't eat until then.
- Hidden Depths: Arthur seems interested in Joan of Arc's story when Miss Turner mentions it as a possible report topic.
- Hypocrite: Arthur tells off Francine for being offended about being called a "marshmallow" because she had called him much worse, and is a mean person to begin with.
- Library Episode: Arthur and Francine visit the library to do research for their report, but forget about closing time and, as the title says, they get locked in.
- Locked in a Room: The main plot of the story, and where Arthur and Francine must put aside their differences in an attempt to get out of the closed library.
- Meat-O-Vision: When Arthur is starting to get hungry while locked in the library, he reads through a gourmet magazine and imagines a pile of books in front of him becoming a nice gourmet meal. He tears part of a page off the magazine he's reading and eats it.
- Series Continuity Error: Prunella can be seen in Mr. Ratburn's third-grade class with the rest of the main kids, even though she is supposed to be in fourth grade
- Stating the Simple Solution: Francine simply demands an apology from Arthur and she'll let the "marshmallow" insult go. He never does, for some reason.
- Stock Scream: Anyone who's watched enough Arthur episodes would know that the scream Arthur thought was Francine but turned out to be from a horror movie was often used for other females screaming in the series.
- What You Are in the Dark: Alone in the closed library, Arthur hears a scream and assumed something bad was happening to Francine. Bear in mind that at this point, Francine has been feuding with Arthur over the "marshmallow" insult, and they're on anything but good terms right now. All the same, Arthur comes to her aid because he was worried for her. As it turns out, Francine was just watching a scary movie in the break room, which Arthur chews her out for making him think she was in trouble. At hearing he came to her rescue, his spontaneous kindness is rewarded when she offers to share the pizza she found.
Arthur is collecting quarters for a school fundraiser for the fire department, and leaves them with Mrs. MacGrady before leaving with Buster Baxter, now acting like a private detective, for the arcade. When Mr. Haney learns MacGrady never got the quarters, he accuses Arthur of stealing them and punishes him with detention and missing the upcoming third-grade picnic. Now Buster has to use his detective skills in order to prove Arthur is innocent.
Arthur Accused! contains examples of:
- Action Prologue: The Teaser features Buster starting the story with Arthur in detention on the day of the third-grade picnic, only to hear a crowd chanting his name approach the classroom he's in. But as the doorknob turns, Buster narrates, "But I'm getting ahead of myself. Let's go back to the beginning." and the episode's title card plays.
- Artistic License – Physics: Adding metallic objects to a pastry recipe, then placing that pastry in a high-powered oven, would certainly cause some sort of reaction—smoke, a bad odor, the brownies not forming properly, a significant shift in weight (note that the batter overflowed because the quarters were added)...but somehow Mrs. MacGrady fails to realize that there are large coins in the brownies she's made.
- Clear Their Name: Buster must do this in order for Arthur to go with the rest of the kids to the third grade picnic.
- "Eureka!" Moment: When Buster fails to solve the case, the Brain sympathizes with him, remarking that his head feels "overflowing with information" when he's stuck with a tough problem. The word "overflowing" allows Buster to finally realize what happened to the quarters: Mrs. MacGrady inadvertently poured them into her brownie mix.
- Evil Laugh: Arthur gets an epic one in Buster's Imagine Spot of him as a master quarter thief. The closed captions for the sequence even read "Laughs maliciously."
- Fair Play Whodunit: All of the evidence needed to know what happened to the quarters is presented onscreen, so viewers can solve the case alongside Buster.
- Is This Thing On?: When the third-graders are all lining up onto the school bus for their picnic, Mr. Haney asks this when trying to speak through an electronic bullhorn, and flips a switch causing a burst of feedback.
- Miscarriage of Justice: Arthur gets sentenced to a week of detention among Mr. Haney and Miss Tingley suspecting Arthur of stealing the quarters, without even fairly questioning him or anything.
- Mystery Episode: Arthur and Buster team up to figure out what actually happened to the quarters that were meant for Mrs. MacGrady.
- Oh, Crap!: Buster after telling Mr. Haney and Miss Tingley about Arthur getting a high pinball score and how one time he did so and had to use up all his birthday money. This is because his story made it sound like Arthur used the quarters meant for the fundraiser at the arcade.
- Pooled Funds: Buster has an Imagine Spot of Arthur diving into a huge pool of quarters ala Scrooge McDuck when considering that Arthur may have indeed stolen the quarters.
- Poor Communication Kills: Overlapping with "Could Have Avoided This!" Plot. When Arthur arrives in the school kitchen to drop off the quarters for Mrs. MacGrady, she's on the phone and too distracted to notice what's going on. Had Arthur interrupted her to tell her what he was doing, or if she'd hung up the phone to talk to him, she wouldn't have mixed the quarters into the brownie flour.
- Private Detective: Buster Baxter gets a new detective kit and starts acting like one of these, complete with trenchcoat, large fedora hat and magnifying glass.
- Private Eye Monologue: Much of Buster's narration.
- Satchel Switcheroo: The crux of the mystery: the bag that Mrs. MacGrady uses to store flour is identical to the one Arthur uses to stash the quarters from the fundraiser. She inadvertently pours the contents of both bags into the brownie mix.
