The Multiplying Mysteries of Mount Ten

by Krista Van Dolzer

  The other boy held up his hands. “Hey, it wasn’t me,” he said. “And I’d take credit if it was.”

  That was probably true. We’d have to focus on the silent types.

  “What about Ravi?” I asked. “He knows a lot about ciphers.”

  “So do we,” Marshane replied.

  “What about Whistler, then?” I pressed. “Or that kid with the glasses? What’s his name?”

  “Who, Keith?” Marshane replied.

  “Yes, Keith!” I said elatedly. “I’ve barely heard him say three words. Don’t they say serial killers are usually quiet and withdrawn?”

  He shook his head. “It can’t be him.”

  “How can you be so sure?” I asked.

  “Because whoever came up with the cipher clearly had access to a printer.”

  “What are you saying?” Graham replied. “That one of the counselors is the killer?”

  I scowled at no one in particular. “Or that Director Verity is.”

  Munch tilted his head to the side. “Why are we assuming that the killer came up with the cipher? Couldn’t it have been someone else?”

  That thought hadn’t crossed my mind, either, but that didn’t make it true. “Why would someone else invent a puzzle? Especially when the killer’s already demonstrated his twisted sense of fun and games.”

  “This is a math camp,” Marshane said. “We all have a twisted sense of fun and games.”

  I couldn’t disagree with that. “All right, then, Graham, Marshane, I want you working on the cipher.” They clearly knew what they were doing, and if they had a special project, it might keep them out of trouble. “The rest of us will work on figuring out the killer’s clues, since we know who’s behind them.” I pulled the bobby pin out of my pocket. “And since we now have ample proof that he’s got Angeline and Toby.”

  The bobby pin caught a shaft of sunlight and bounced it around the room, filling the math nerds’ eyes with an almost eerie glow.

  “I found this bobby pin, which is clearly Angeline’s, under the old-fashioned typewriter producing all the clues. I also found a bunch of textbooks.” I returned the trinket to my pocket, then consulted my sketchbook (since I’d scribbled down the titles as soon as I’d gotten back to my room). “Introduction to Logic, A Concise Introduction to Logic, and something called The Game of Logic—though, for the record, that one was easily the most concise.”

  Federico looked up from the lines he’d been tracing on his palm. “That’s the Holy Trinity right there, at least when it comes to logic textbooks.”

  I leaned forward in my seat. “But isn’t logic, you know, logical? Why would someone need to write an entire textbook on it?”

  “Oh, there are all kinds of applications—law, engineering, computer science.” He returned his attention to his palm. “But the best ones are the games.”

  I perked up. “The games?” That made me think of Sphinx’s note.

  Federico nodded. “Haven’t you ever done a logic puzzle? I have to say, they’re wicked fun.”

  “Do you think that’s what this is?”

  I spread the clues out on the floor. I’d been numbering them in case the order was important. Some of them were now so mangled that they looked more like confetti:

  1. Satyr and Minotaur share a cabin with two other monsters.

  2. Siren has a nickname.

  9. Minotaur’s first name begins with the same letter as Hydra’s last name.

  5. Phoenix wears glasses.

  3. Hydra and Cyclops are involved in a not-so-secret fling.

  4. Centaur, Griffin, Unicorn, and Manticore share a cabin.

  6. Unicorn’s nickname begins with the same letter as Manticore’s first name.

  8. Harpy is a girl.

  7. Cyclops and Chimera share a cabin with no other monsters.

  “It could be,” Federico said. He pinched the worst offender between his thumb and index finger, holding it up like a dead rat. “But it’s hard to say for sure.”

  I pressed my lips into a line. When had it become my fault that the clues weren’t holding up? “I have the list right here,” I said as I handed him my sketchbook. “But I don’t have the solution.”

  Federico turned the pages slowly, like the sketchbook was sacred. “Well, that’s probably because you haven’t used a grid,” he said.

  I perked up again. “A grid?” I knew something about grids.

  Federico shrugged. “It’s just a graphic organizer.” He motioned toward the pencil tucked behind my ear. “May I?”

  It was weird to see him acting so unlike his normal self—up until he’d started gushing about books and logic puzzles, I couldn’t remember the last time he’d said something without bouncing—but it made me think that maybe he did know what he was doing. I handed him the pencil. If he had a problem with my earwax, he’d have to find a way to deal.

  “So let’s say you have three people with three different types of dogs who line them up for a race. The catch is, you have no idea which dog belongs to which person or which place the three dogs took. You only have a list of clues.” He drew three three-by-three grids—one in the middle of the page, one connected on the right, and one connected on the bottom. Then he labeled the horizontal axes PEOPLE and TYPES OF DOGS and the vertical ones PLACES, and TYPES OF DOGS again. “These grids will help you work it out.”

  “Who are the people?” Graham replied. “And what are the types of dogs?”

  Sighing, Federico scrawled BOB, BETTY, and BARTHOLOMEW above the three columns marked PEOPLE; PIT BULL, SCHNAUZER, and GREAT DANE above the three columns labeled TYPES OF DOGS; 1ST, 2ND, and 3RD next to the three rows labeled PLACES; and PIT BULL, SCHNAUZER, and GREAT DANE next to the three rows labeled TYPES OF DOGS. “There, you happy now?” he asked.

  Marshane shook his head. “You could have picked any type of dog, and you settled for a schnauzer?”

  “And what kind of name is Bartholomew?” Graham asked.

  Federico threw his arms up. “Those details are not important!” He tapped the page for emphasis. “What’s important is the grids.”

  I picked the sketchbook up again and gave the grids a closer look. Then I flipped back a few pages and reread the killer’s note.

  “But this doesn’t say anything about types of dogs,” I said. “And we’re not running a race.”

  “It was just a dumb example.”

  “But without the dogs, the race, how are we supposed to label these other two grids?” I asked.

  Federico took the sketchbook back. “I really don’t know,” he admitted after he reread it, too. “Also, it won’t work if we don’t have every clue, so unless we’re completely certain that we’ve tracked all of them down”—he snapped the sketchbook shut—“we won’t be able to solve it.”

  “Then we’ll just have to be certain.” We could deal with the grid later; first, we had to find the clues. “Has anyone found any more?”

  The math nerds shook their heads.

  “Well, keep an eye out,” I said gruffly. If the killer only won because we couldn’t find his clues, I would be very put out.

  Graham reviewed the note that I’d gotten from the killer. “If this is a logic puzzle, we’re gonna have to figure out which monster is which person. Then we’ll know who the killer is.”

  “And who he’s gonna kill,” Marshane said grimly.

  “He’s not gonna get the chance. We will find Angeline and Toby before the killer can off them.” I snatched the note away from Graham. “At least we already have one piece of the puzzle figured out.”

  Federico shook his head. “The story makes it sound like there’s only one victim. And if this is a logic puzzle, then there’s only one solution.”

  I tilted my head to the side. “Maybe it didn’t mention them because the killer knew that they’d already be out of commission.” I locked eyes with the others. “Which, unfortunately, means he’s coming after someone else.”

  CHAPTER 21

  We spent
the rest of the night trying to figure out the grids (or just skip straight to the solution), but we didn’t make much progress. By the time we had to go to bed, we’d only managed to come up with a list of scribbled-out guesses.

  I dismissed the other math nerds, then tripped upstairs to my room. Moonlight spilled through the sliding door, bathing Angeline’s cold bed in a ghostly, washed-out glow. I shook off the creeps that tried to shiver down my spine. She wasn’t dead. She couldn’t be.

  Brooklyn looked up from the suitcase she’d never bothered to unpack. “Have a meltdown if you must, but keep your bodily fluids to yourself.”

  I was too tired to fight back. “Why do you do that?” I asked.

  “Why do I do what?” she growled.

  “Treat everyone like sludge,” I said.

  Brooklyn rolled her eyes as she flopped onto her bunk. “I don’t treat everyone like sludge, just useless hacks like you.”

  I didn’t take her bait, just stood there blinking, thinking. She pretended to ignore me, but I could tell I’d gotten to her.

  “Do you want to talk about it?”

  “With you?” she asked, scoffing.

  My only answer was to nod.

  Brooklyn scratched her nose and sighed. “My dad is in the Air Force, all right? He’s been on, like, six tours of duty, so now he seems, I don’t know, different.”

  Though I’d hoped she would open up, I hadn’t expected her to. “Is he angry?” I whispered. I’d certainly be angry if I’d been forced to go to war.

  “Sometimes,” she admitted. “But most of the time, he just seems … empty. Like he left the most important pieces of himself back there.” She dragged a hand across her face. “Still, that’s no excuse. I’ve been a moron, and I’m sorry.”

  “Apology accepted,” I replied. “That must have taken lots of guts.”

  Brooklyn rolled her eyes. “Now you sound like my therapist.”

  I grinned despite myself. “You know what they say about great minds.”

  “Don’t think this little chat makes us besties now,” she said.

  I tilted my head to the side. “Do you think we could be friends?”

  She made an unflattering noise that sounded exactly like a snort, but just before she rolled away, I spied her mouth. And it was smiling.

  I couldn’t help but smile, too, as I changed into my pajamas and burrowed deep under the covers. It was way colder in these mountains than I’d ever thought it could be (or maybe that was just because my spirits were chilled to the bone). Either way, I couldn’t sleep, so I clicked my flashlight on and cracked my dog-eared sketchbook open. But the clues were no more understandable than they’d been earlier. I dug my fists into my eyes, but the darn words just kept swimming. Maybe Brooklyn had it right. Maybe I was a useless hack.

  I pushed those thoughts out of my head. Moping wouldn’t solve this problem or save Angeline and Toby. After drawing a deep breath, I turned over the last page and dug out a pencil stub. I needed to get out of my head, let my thoughts float for a while. The only way I knew how to do that was by sketching, sketching, sketching.

  I started with some random doodles. Doodling usually calmed me down, but tonight, it revved me up. I turned the page over again and pulled my phone out of my pocket. If I wanted to calm down, I would have to go all in.

  I couldn’t help but grin as I thumbed through the pictures I’d taken. There was Munch. There was Marshane. The one of Toby in that apron nearly made me laugh out loud. But then I remembered he was missing, and the laugh died in my throat. Toby was the kindest, gentlest man I’d ever met. He shouldn’t have been made to suffer for my sheer stupidity.

  Blinking the tears out of my eyes, I laid a grid over his face. My fingers knew what to do next, so my brain had time to wander as I penciled in the lines. Before long, the list of clues was steadily cycling through my brain along with our scribbled-out guesses. If Minotaur shared a cabin with three other monsters, it had to be one of the boys. And if Harpy was a girl, it couldn’t be one of the boys.

  By the time I realized I’d labeled the horizontal axis MONSTERS and the vertical one PEOPLE and was penciling in our names, I couldn’t blink, could barely breathe. This was the piece that we’d been missing. This was the start of the solution.

  We didn’t need an L-shaped grid. We needed one enormous one.

  I couldn’t wait to show my work to the others the next morning. I threw on my nearest clothes, then stuffed my sketchbook down my shirt and hightailed it out of there. When I slapped my sketchbook down and Federico’s eyes lit up, I knew that I was onto something.

  But the grid was useless on its own; we still had to fill it in. And before we could do that, we had to finish labeling it. We put the monsters on one side, but the people wouldn’t fit. Even after we added ourselves, the other math nerds (Oliver, Whistler, Ravi, Keith, and Brooklyn), the counselors (Mr. Pearson, Mr. Sharp, and Ms. Gutierrez), and Director Verity, we were still one person short.

  We spent the rest of the day trying to figure out who it should be.

  “It should be Angeline,” Graham said. “She’s been a part of the camp from the very beginning.”

  We were back down at the amphitheater, soaking up some much-needed sun while the director tried to teach us about animals’ survival and competing population-growth rates. We were supposed to be working on our graphs (trout versus mayfly), but every time she turned her back, I would flip my paper over and tinker with the grid. I’d drawn it so many times I could have drawn it in my sleep.

  “We can’t add Angeline without adding Toby, too,” I growled. “He also disappeared, you know.”

  “Yes, but your stepdad wasn’t supposed to be here,” Graham replied.

  I threw my arms up. “Yeah, well, neither was I!”

  I must have screamed that last line, because Director Verity stopped and glanced over her shoulder. “Are you quite all right, Esther?”

  “I’m fine,” I said through gritted teeth. “I must have gotten a Corn Nut stuck in my throat.”

  “Well, be careful,” she replied. “I’m afraid emergency services take some time to get up here.”

  Was that supposed to be some kind of threat?

  Stretching to cover my shiver, I returned my attention to the grid. I straddled my bench so I could look at the grid from a new perspective, but I only succeeded in scratching my legs on the log’s gnarly bark. When a speckled beetle scurried across my paper, I didn’t flick it away. It could probably solve this puzzle as easily as I could.

  Marshane lay down on his log. As he was so fond of telling us, he thought of himself as the think tank, not the scribe. “Didn’t we decide to leave out Angeline and Toby?”

  Graham rolled his eyes. “Then who gets the last slot?”

  I sat up straight. “Archimedes. Has to be.”

  I didn’t know why I hadn’t thought of it before. I already suspected him, but he couldn’t be Sphinx if we didn’t include him. With a quaking hand, I quickly added his name.

  The grid was ready to go.

  I started penciling in some of the clues I remembered, but before I had a chance to get into a groove, Director Verity said it was time to head back.

  While we were picking up our stuff, Marshane sidled up to me. “We did it,” he whispered.

  “You did what?” I whispered back.

  “We decrypted the cipher!” Graham replied, appearing on my other side.

  I looked back and forth between them, searching for some sign of deception, but the smiles on their faces were too open to be fake.

  Graham held out a scrap of paper that had been folded in half. “It says, ‘If you know what’s good for you, then you’ll stay out of my workroom.’ ”

  I crinkled my nose. Whatever I’d thought it would say, that definitely wasn’t it.

  Graham unfolded the scrap, revealing the contents of the cipher in his surprisingly sleek handwriting:

  BO YKU DJKW WAFT’S RKKI OKQ YKU, TAMJ YKU’GG STFY KUT KO HY WKQDQKK
H

  IF YOU KNOW WHAT’S GOOD FOR YOU, THEN YOU’LL STAY OUT OF MY WORKROOM

  “At first, we thought the K had to be an E,” he said.

  “Or an A,” Marshane replied.

  “But then Marshane pointed out that Y-K-U appeared three times, once as a contraction, so it seemed a lot more likely that the K was another vowel, O, and that Y-K-U was ‘you.’ ”

  “Once we had that K was O, we plugged that into the cipher and saw what else we could come up with. When K-U-T turned into O-U-T, ‘out,’ we knew we had to be dealing with a classic keyword cipher.”

  I snatched the scrap out of his hands. “That isn’t much of a cipher.”

  Marshane snatched it out of mine. “That’s because of the keyword. So let’s say it was ‘Esther’—or E-S-T-H-R, since you can’t use a letter twice.” He scribbled that down on the scrap. “Then you start at the beginning of the alphabet, so your As would become Es, your Bs would become Ss, your Cs would become Ts, your Ds would become Hs, and your Es would become Rs.”

  A B C D E

  E S T H R

  While Marshane quickly wrote down the rest of the alphabet, Graham picked up the explanation: “Then you keep going with the letters that don’t appear in the keyword—starting with the A, of course—so in Marshane’s made-up example, the F would become an A, the G would become a B, the H would become a C, and the I would become a D.”

  A B C D E F G H I

  E S T H R A B C D

  “But then you’d have to skip E since it appeared in the keyword, so your J would become F.”

  Graham nodded absently. “You would keep going like that until you got to the T in the normal alphabet—”

  “Which would become Q,” Marshane added.

  “—and then the rest of the letters would just be themselves,” Graham said as if Marshane hadn’t cut in. “Since T is the last letter alphabetically in ‘Esther,’ the letters after it don’t shift.”

  “So if we go back to our cipher”—Marshane flipped the scrap back over—“as soon as we knew the T was T, we also knew the letters after it had to be just themselves, too.”