The Mystery of the Missing Yearbook Photo: What Is a Graph, Anyway?

The fluorescent lights of Oakwood Middle School’s library flickered overhead as Luna slammed her locker shut so hard the metal creaked. Her yearbook—the one she’d spent three weeks begging Mia to let her edit the layout for, begging her mom to buy the new pink high-top sneakers for the photo shoot, begging Javi to stop making faces in the background of every test shot—was supposed to launch in 12 hours at the end-of-year assembly. And her photo? The one where she wasn’t blinking, where her curly ponytail wasn’t half falling out, where she wasn’t making a weird face because Javi had told a bad joke right as the camera clicked? Gone.

She’d stuffed the printed 4x6 in her locker yesterday afternoon after the yearbook club meeting, right on top of her math textbook, and when she’d swung by the library between classes to grab it for the final proofread, the locker had been empty. Not just the photo—her limited-edition *Spy x Family* Anya keychain was gone too, the one she’d won at the regional AI hackathon last month.

“No, no, no, no,” she muttered, yanking open the locker again so hard the hinge squealed. Her phone buzzed in her pocket: a text from Mia, the yearbook club president, who’d been her partner in crime for the entire photo shoot. *U in the library? My USB with all the yearbook files is gone too. I left it in the yearbook club locker yesterday. I’m gonna throw up.*

Luna’s stomach dropped. First her photo, now the entire yearbook’s files? She’d spent 20 hours last weekend fixing the layout of the chess club’s page, making sure Anya Martinez’s photo was front and center because Anya had finally beaten her in a tournament after three months of losing. If the files were gone, all that work was lost, and the yearbook would print with last year’s blurry chess club photos and the principal’s 2018 headshot.

She sprinted to the yearbook club room, skidding to a stop in the doorway where Mia was hunched over a desk, head in her hands, and Javi was leaning against the wall, scrolling through his phone with a scowl.

“My mechanical keyboard is gone too,” Javi said without looking up. “I left it in the computer lab last night. The one with the custom keycaps shaped like circuit boards. I saved up six months for that.”

Luna’s head was spinning. Three items, three different locations, all gone within 24 hours. This wasn’t just a random prank—this was targeted, or at least, connected. She’d spent the last six months teaching herself AI through free online courses, building a cat recognition model for the school’s animal shelter, even entering a regional competition where she’d used a graph neural network to predict which students would join the robotics club. She’d aced the unit on graphs last week, but she’d thought it was just abstract math, something for coding competitions, not something she could use to find her missing photo.

Wait. Graphs.

She’d used graphs to map out character relationships in *Jujutsu Kaisen* last month, when she’d been writing a fanfic about Gojo and Geto’s high school years. She’d made a node for every character, then drawn lines between them for “teacher”, “student”, “rival”, “friend”. It had helped her catch plot holes she’d never noticed before—like the fact that she’d written a scene where Geto and Gojo were in two places at once, because she’d forgotten they were classmates who always hung out together.

“Guys,” she said, leaning against the doorframe, breathless. “I know how to find the stuff. We build a graph.”

Mia looked up, eyes red. “A graph? Like the math kind? We have 12 hours to fix the yearbook, Luna, I don’t have time for extra credit.”

“Not the math kind—well, it is math, but it’s also just… mapping connections,” Luna said, pulling up a chair and sitting down. “Remember when I showed you that *Spy x Family* character map I made? Every character was a dot, and the lines between them were relationships. That’s a graph. We can make a graph of everyone and everything connected to the missing stuff, and see who shows up in all the right (or wrong) places.”

Javi’s head snapped up. “Oh! I did that for the computer club last month! We had a bug in our hackathon project, and I made a graph of who worked on which part, who had access to which files, and we found the bug in 10 minutes. That’s actually genius.”

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2.1 Nodes: Everything You Care About Can Be a Dot

If you’ve ever doodled in the margins of your notebook during a boring lecture, you’ve probably already drawn a graph without knowing it. Maybe you drew little circles for all your friends, then lines between the ones who date each other, or circles for all the characters in your favorite anime, with lines for who’s friends with who, who’s dating who, who’s trying to kill who. Those circles? Those are nodes (sometimes called *vertices*, but let’s be real, “node” is way cooler and easier to say).

A node is just any “thing” you want to study. It can be a person, a place, an object, an idea, even a feeling. If you’re mapping your friend group, your nodes are your friends. If you’re mapping the plot of *Attack on Titan*, your nodes are the characters, the walls, the titans, the Survey Corps. If