“Same handwriting,” Eddie observed.

I nodded in agreement. “Yeah, too bad we don’t have an easy way to trace—do you hear that?”

I could tell from Eddie’s face that his quicker hearing had already picked it up. Ms. Terwilliger took a little longer to notice. “Like buzzing . . .” She glanced up into the Raptorbot’s metal face. “From that.”

The buzzing grew louder and louder, and Eddie hurried forward to put himself between the display case and us. “Get back!” he shouted, just as the Raptorbot’s mouth opened and several dozen glowing objects came flying out. They came at us with unbelievable force, and I fell backward, landing awkwardly on my side. I held up my hands to block the glowing swarm, but some of them still grazed my face as they passed by. I cried out at the contact, which stung like a million paper cuts.

“What are they?” I managed to exclaim.

“Fotianas,” Ms. Terwilliger called back. She too had hit the floor and was covering her face as the swarm came by for another pass.

“Foti-what?” asked Eddie.

“They’re from the same realm Hopper comes from, but they’re much less friendly.” She cautiously removed her hands from her face so she could get a line of sight on the creatures. “Think of them as mutant fireflies.”

Eddie, ever ready to improvise, grabbed the welcome sign from the robot standing at the doorway. Wielding it like a baseball bat, he swung it toward the fotianas as they came toward him. As though they shared one mind, the swarm parted so that his “bat” hit mostly open air. Only a couple of the fotianas were too slow. They disintegrated into sparks as they were struck. That was encouraging, at least, but we had a lot more of them to get through. Things grew more complicated when the swarm split into three and came after each of us.

I had just gotten to my feet, but as I saw the group targeting me—in an arrow formation, even—I tore across the room and managed to duck under the conveyor belt’s table just in time. “What’s the best way to get rid of them?” I yelled to Ms. Terwilliger. “Fire?” Across the room, I could see Eddie continuing to nick away at them with his sign, but their speed and agility kept him from making significant progress.

“I don’t want to burn this place down,” she called back, trying to dodge as the swarm chasing her passed nearby. They swiped her arm, leaving tears in her sleeve and small bloody cuts visible on the skin beneath. As soon as she had some distance between her and them, she held up her hands and chanted a Latin incantation I’d never heard before. A hundred tiny sparkling crystals appeared in the air before her, and with another command, she sent them flying into the fotianas. Where the crystals struck, the “mutant fireflies” vanished into sparks.

The swarm chasing me flew low, trying to run me out from under my table. I waved them off, getting my hand stung in the process, as I parsed Ms. Terwilliger’s spell. It had been very similar in word and feel to my old friend the fireball spell, with just a few notable differences. It was an ice spell, I realized. Thrown with enough force, bits of ice could have the impact of little razors.

I scurried out from under my table and tried to put some space between my swarm and me. Behind me, I heard Ms. Terwilliger once again reciting the spell. Hoping I had the words memorized, I attempted the same feat, using the same motions and gestures I would for the fireball spell. Power coursed through me, and ice crystals shot forward at my command. But my aim wasn’t as good as Ms. Terwilliger’s. Although the spell’s structure was similar to that of the fireball, the feel of it was different and required practice. I only managed to take out a few of the fotianas that time but had more success on my second and third attempts. Whenever I paused to recast, they wasted no chance to come at me, causing more irritation and pain. I would wave them off and cast the spell again, gradually picking off their numbers.

I lost track of time until I caught sight of a second cluster of ice crystals joining mine as I sent them into the significantly smaller fotiana flock. Out of the corner of my eye, I saw Ms. Terwilliger waving her hands. A moment later, Eddie came striding forward as well, still wielding that sign. They’d both defeated their respective swarms. Mine was the only one left, and within minutes, my friends helped me finish off the last of them.

Without the buzzing, the room suddenly took on an eerie silence. We all stood still, chests rising and falling heavily, as we looked around the dim room for any further signs of danger. Eddie and Ms. Terwilliger’s faces both showed cuts and scrapes where the fotianas had touched them, and from the stinging of my own skin, I assumed I looked the same. We were alive, though, and the threat seemed to be neutralized for now.

“Where’s the envelope?” Eddie asked at last.

I hurried over to where I’d dropped it, back by the Raptorbot, who had just surveyed our altercation from his lofty display. The ice crystals had melted into puddles on the floor, and one corner of the envelope was soaked as a result. Otherwise, it seemed undamaged. I carried it over to my friends and turned to Ms. Terwilliger before opening it.

“Do you sense anything?” I asked.

“If there’s a spell, it’s very cleverly concealed.” She held up her hand and a small burst of fire appeared in her palm. “I’ll be ready, just in case.”

The envelope was heavy and bulky, so I wasn’t entirely surprised when I found a brick inside, even though I had no clue what its purpose could be. It appeared to be made out of some sort of sandstone. I glanced at my companions to see if it made sense to them, but they looked as puzzled as I felt. I reached back into the envelope and pulled out a map of the Missouri Ozarks.