Free Click Here to Start by Denis Markell

eighteenth was circled. So try page eighteen.”
    I pull it away from him and thumb through the issue to the right page. There in ink, in the margin, is written “9554.”
    Caleb looks back at the calendar and smiles. He maneuvers his way over to it and carefully removes it from the wall. Behind it is a small safe. With four numbered wheels.
    He enters the code into the wheels and the door swings open.
    “Uncle T, you made this too easy. Even I knew that one,” crows Caleb. He reaches in and pulls out a bulb and a scrap of paper. Examining the paper, Caleb looks annoyed. “It’s blank.”
    “Bring them here,” I instruct Caleb. Carefully, I plug the lamp into the wall and screw the bulb in. It glows with a faint purple light.
    “I should have known,” Caleb groans.
    “What is it?” Isabel asks, looking down as I hold the paper under the light.
    Like magic, a series of numbers appears.
    “UV light,” Caleb answers. “You see it in games all the time. The ink only shows up under ultraviolet light. That’s like the easiest thing in the world and I missed it.”
    “ ‘475, 570, 400, 510, 650,’ ” I read off. “It’s a series of some kind….”
    “What has three numbers?” Isabel asks. “It’s not a date. Could be a serial number or something? Maybe on one of these old radios?”
    “I got it!” Caleb says proudly. “You move the hands of that clock on the wall to all these times, in sequence. That’s so old. It’s like in practically every other game!”
    Oh, poor, sad deluded Caleb.
    I break it to him gently. “Only one problem. There isn’t any time that’s 475…or 570.”
    Isabel peers closely at the page. “Turn it over,” she suggests. “There!” She points. “There’s something else written on the back!” Unlike Caleb, Isabel doesn’t seem to miss a thing.
    “I
never
remember to look on the back,” mutters Caleb, shaking his head. He reads out what’s typed on the back. “ ‘540.45 DDS.’ ”
    “That one’s easy,” Isabel chirps. “It’s referring to a science book.” Both Caleb and I stare at Isabel openmouthed.
    I know from Google that it’s a book, and even know which one it is. But how does
she
know?
    “Maybe,” I say, trying not to sound too impressed.
    “How the heck are you so sure about that?” marvels Caleb.
    “It’s the Dewey decimal system,” says Isabel, peering down at the bookshelf. “ ‘540’ refers to the sciences. My guess is there’s some science book here somewhere that might have the—”
    “You know the Dewey decimal system numbers by heart?” I ask incredulously.
    Isabel looks at me like I’m the weird one. “Of course. Anyone who spends enough time in a library, you just learn stuff, you know?”
    We cross to the grimy bookshelf against the wall on the far side of the apartment. It’s immediately clear which book it is. Unlike the others, it isn’t covered in dust. It’s sitting by itself, on its side. Isabel picks it up and reads the title out loud: “ ‘
Ultraviolet and Visible Spectroscopy: Chemical Applications
by C. N. R. Rao.’ ”
    She looks up at us. “One page is dog-eared.”
    Isabel turns to the page and reports, “It’s a chart.” She reads from the bottom: “ ‘The visible spectrum, as divided by wavelength.’ Yep, the numbers seem to be similar to what’s here.” She looks up at me quizzically. “But how do we use them?”
    “Whoa, slow down,” Caleb says, peering at the book over her shoulder. “What exactly do the numbers correspond to?”
    “The colors in the visible spectrum. Each number seems to represent a different color.”
    Something clicks with Caleb. “Yeah, there was something like this in a game called
Escape the Lab.
Remember?”
    I nod. “You set up glasses in such a way that the colored liquids in them corresponded to the order in the note.”
    Caleb looks around. “The only problem is that there are no test tubes…or bottles…or prisms…or anything I can see