A TV crew for a ghost-hunting show has set up in Bailey, Indiana, to try to find evidence of paranormal activity, and seventh grader Lennie Miller has mixed feelings about it. Lennie is a Pattern Finder. She can see the supernatural creatures from the Mystical Realm that cross over into our world, and they search her out to help them solve their often-unusual and always-complicated math problems. It’s a role that Lennie would happily give up. And now, with a TV crew in town, that might actually happen.

The creatures in the Mystical Realm are worried about being discovered. If they are, they’ll have to move the Mystical Realm to another location, and they’ll have to find themselves another Pattern Finder. The idea excites Lennie…mostly. It would be great not to have to solve so many weird problems, but without the otherworldly creatures around, would life become boring in her tiny rural town?

While Lennie wrestles with this dilemma, she and her best friend Gil must solve a variety of paranormal problems, many of which are related to trying to keep the Mystical Realm hidden, such as determining the sizes of crop circles so they can be regrown, figuring out where a warrior on a flying dragon needs to drop a deterrent from the air to hit a certain spot on the ground, calculating the best escape plan for a vampire and a werewolf, computing the interest rate on a loan to move the mystical threshold, and determining the best location for adding a neutralizing formula to a glowing river as the chemicals break down and flow downstream.

Throughout, Lennie struggles with whether or not she should be solving these problems at all. If she simply did nothing, the TV crew would undoubtedly discover the Mystical Realm, and she would never have to solve another problem for the creatures that live there. It would sure be nice to be a normal kid again. Or would it?