"This is the WORST POSSIBLE THING!"
"Calm down, Twilight," Spike advised, his own voice a little bit frantic and high-pitched. "When Rarity says that we all know she doesn't really mean it, but you sound like you're actually serious!"
"I am serious!" Twilight grabbed Spike with her magic and pulled him to her, putting her hooves on his small shoulders and staring him directly in the eyes, face to face. "There are three hundred books missing with no record of who checked them out! This is horrible! Ponyville is going to throw me out of their library and exile me for being the worst librarian ever! Princess Celestia sent me to do this job and she'll be furious with me! Three hundred books!"
"I know it's a lot, but--"
"There's only six thousand books in the library total! FIVE PERCENT OF ALL THE BOOKS ARE GONE! No record of who checked them out! Or when! Or where!"
"Maybe we should talk to the police? Three hundred missing books is too many for us to just have missed checking out for ponies. Maybe somepony stole them!"
Twilight's hoof flew to her mouth. "That's it! Of course, Spike, that's brilliant! Of course somepony must have stolen them!" She reviewed the list of missing books. "There might even be a clue to who did it in the pattern of the missing books!"
"Somepony who liked comedy, I'm guessing," Spike said, pointing out the totals broken out by genre. "Two thirds of the humor section's missing."
"It couldn't be Pinkie, could it?"
"No way, Pinkie wouldn't steal from us!"
"I know, I know, but what if she went to check the books out and we weren't around so she tried to check them out for herself only she didn't know how to do it exactly right so she left the records someplace she thought we'd find them except it's Pinkie so who knows where she would have left them? We have to go ask her!" She started for the door.
"Whoa whoa!" Spike stood in front of the frantic unicorn, paw held out. "Pinkie knows how to check books out ‘cause she helped me out one time while you were doing some kind of research project! It can't be her."
Twilight deflated. "No, you're right," she said sadly. She'd been so hoping that was it; if the books had been taken by Pinkie, then nopony had stolen them and it would be easy to get them back. But Pinkie wouldn't have had an interest in history, not enough to check out almost every book pertaining to Equestrian history post-Discordian era. And certainly Pinkie wouldn't have taken out books on recent discoveries in physics and advanced mathematical theorems. "It couldn't have been Pinkie. But who would have stolen three hundred books? And how? If they took them all at once we'd have noticed! Even if they broke into the library while we weren't here, we'd have seen that many missing books!"
"I don't know, but I first started noticing books missing right after I got back from accidentally going to the... I mean spending a week sitting everypony's pets. And that was just a week ago!"
"So you think somepony took them while I was in the Crystal Empire dealing with the inspector for the Games? But how would we not have noticed so many books missing at once?"
"I don't know. Maybe a spell?"
"No, I'd have definitely noticed a spell." Twilight considered. "You said some books started being missing last week, but a lot of these books from the general fiction section are classics or bestsellers. We'd have noticed this many bestsellers missing if they'd all gone at the same time. I think maybe the thief has been coming back for more books. Maybe they took a bunch of books while we were gone, and they've been adding to it periodically."
Spike nodded. "That makes sense. That'd be why we didn't notice so many gone until we had all those problems today and closed to take inventory." Golden Oaks was not a busy library. Ponyville wasn't a large town to begin with, and it wasn't a hotbed of intellectual interchange, not like a small college town such as Ithacolt or Ponypsie. But it got busy on Saturdays, because ponies were looking for fun things to do for the weekend, and reading a best selling novel was a pastime most ponies enjoyed from time to time. This Saturday, however, half the bestsellers that anypony had tried to check out had turned out to be missing, so Twilight had closed the library to do inventory... and discovered the horror of three hundred missing books. Three hundred and twenty seven, to be exact. Two thirds of the humor section, almost all of the Equestrian history section, half the plays, a third of the classics, half the graphic novels, and while the books missing from bestsellers, science, mathematics and magic weren't a large percentage of the total of those sections, the missing books were the most recent ones, and therefore the most popular. Well, the new books on advanced magical theory weren't popular with anypony but Twilight, but she'd really been looking forward to reading them.
"Well. If there's a thief who keeps coming back for more books, then I know just what to do!"
"This isn't going to involve things exploding again, is it?"
Twilight grinned. "No, Spike. I'm going to cast a locator spell on all the books we have. And then as soon as we find there are any other books missing, I can use the locator spell to find the missing ones, and teleport right to the perpetrator! Or at least to his or her stash of stolen books."
"Huh. That does sound like a good idea," Spike said. "But just be careful about the teleporting part, okay?"
"I'm always careful when I'm teleporting!"
From Spike's expression it was apparent that he thought this was of dubious veracity, but he didn't press the issue. "Okay. Should we open the library back up?"
"No, not yet! Taking all the books off the shelf to inventory them has gotten dust all over the place! We need to mop and dust before we can re-open, Spike, that ought to be obvious."
"Well, excuse me," Spike muttered. "Did you know it's a scientifically proven fact that dragons can't see dirt?"
Twilight gave him a look. "Don't ever believe what you read in the popular science section of magazines, Spike," she said.
The next day, around closing time, Spike called to her. "Twilight! I found some of the missing books!"
"Really? Where! Where?" Twilight galloped over to the kitchen and came to a skidding stop.
"Um... in the laundry room."
"In the what?"
Spike handed her a book. "I don't think laundry is the right idea, but it looks like they do need a cleaning."
Was that... cheese all over the book? It was a history of the development of technology in Equestria over the past two hundred years, a dry tome she had never seen anypony check out, ever. But the last time she'd done book inventory, it was in pristine condition. Now there were smushed bits of cheese all over several of the pages... but that wasn't the worst. The worst were the bits of crushed fruit, blobs of jelly, and smears of chocolate. Whoever had been reading this book hadn't even bothered to try to not mess it up with their snacks.
Outraged, Twilight inspected the rest of the stack of books. A Connecticolt Stallion In Princess Platinum's Court, covered in cookie crumbs. She couldn't even tell what kind of cookie; it smelled lemony but looked like chocolate chip. Fractals, Butterflies and the Everfree, potato chips and peanut butter. The Great Fire of Baltimare, rice, seaweed, cucumbers, and blueberries. 1,001 Pegasus Pranks, cotton candy. Fear and Loathing In Las Pegasus, no food, but the heavy water damage and soapy scent suggested it had fallen in a bathtub. Collected Plays of Spear Shaker... bloodstains?
Twilight took a deep breath, eye twitching. "Spike?"
"Um, yeah?"
"You did laundry on Friday. Were these books in the laundry room then?"
"Of course not! If they had been, I'd have brought them up yesterday when we were inventorying all the books!"
"Somepony stole three hundred of my books, Spike," she said. "And then returned seven of them, ruined! Covered in food stains and, and water damage, and I don't even know what this is! So I am going to find them, and I am going to make them pay."
"Three hundred twenty books would be a lot of bits," Spike said. "They might not even have that kind of money."
"Oh no no no. They're not going to pay with bits, Spike. Not with bits at all." She began giggling madly.
"Uh, Twilight, are you okay?"
"I will be. Because the thief will come back, Spike. They'll ruin more books by being a total inconsiderate slob, so they'll come back and steal more. And when they do... when they do, I will find them. And whoever it is, I will make them pay."
"You're scaring me."
"Did you take my books and get food all over them?"
Spike was outraged. "Of course not! Twilight, how could you even ask--"
"It was a rhetorical question, Spike, I know you didn't take my books." She patted him on his head with her hoof. "And that's why you have nothing whatsoever to be scared of. Because nopony who is innocent of taking my books has anything to be scared of! But whoever stole these books... oh, they should be scared. They should be very scared."
"Are you gonna punch them in the face?"
Twilight blinked, the strange question breaking her free of her fit of psychotic laughter. "No, where would you get that idea? You shouldn't punch somepony in the face just for taking your books!"
"Oh, well, that's a relief--"
"But they're going to wish I had, Spike. They're going to wish that all I did to them was punch them in the face. BWAHAHAHAHA!"
"Okay, I am officially going to notify the princess about this. And maybe then get our friends. All of them."
"That's a great idea! Princess Celestia loves books! When she hears about this horrible book thief who ruins the books they steal, she'll want to banish them to the moon! What's left of them after I get through with them, anyway."
"Oookay... I’m going to go write that letter now..." Spike backed away.
Twilight cradled her damaged books in her magical field. "Oh, my books, my poor, poor books," she crooned at them. "Don’t worry, little bookies, Twilight will find a way to fix you. I -- I'm sure we won't have to... throw any of you out for being ruined..." She swallowed. "I'll find a way to fix you and clean you up, somehow. I'll find a spell. When we get all your other book friends back and I have all my spellbooks again, I'm sure of it. I'll save you all."