During the Bon Air boys’ visit to a high-fence wildlife preserve, Frank tested his newest invention: a high-powered, long-distance microphone. In that place, he overheard the voices of unseen men who seemed to be plotting a significant crime. That startling discovery launched him and best friends Frank and Chase on another edge-of-your-seat adventure. Who broke into the home of one of Lewisville’s most beloved citizens, and what was he trying to find in the dark of night? What illegal activity is happening deep in the forest inside the preserve? Why are two bitter relatives conspiring to gain control of property owned by Mr. Rigsby? And who is driving the mysterious truck that threatens the Bon Air boys? These questions and more are on the minds of your favorite young sleuths as they race headlong into their eighth mystery. The surprising answers will keep you guessing until the final pages!