City kid Billy Jo Jive and his friend Sunset pursue their latest detection case at Camp Mountain Lake, where a moaning ""OOOOOOH! AHHHHHH! OHHHHHH!"" fills the boys' bunkhouse with shivers. Wrong Way Willie turns up missing at Billy Jo's roll call (his second night there, Jive is already taking charge), and though the counselor reports later that Willie has transferred to rival camp Smoky nearby, fat Johnnie Jimson disappears the same night, returning in the morning with vague tales of an Echo Lake ghost. It's clearly a case for Private Eyes Billy Jo and Sunset, especially after counselor Hank sneers at the ""little kids'"" efforts. And so the two follow a sneaker trail to a tape recorder in the woods. . . and trace that to Johnnie Jimson, who's been spooking the kids to help out his uncle, Camp Smoky's owner. It's a routine course to an unlikely solution, with Billy Jo's Sesame Street familiarity its only allure.