A beautiful mid-autumn day, just the day for a Sunday drive in the country. At least that's what former journalist Art Parker, his wife, Dr. Marsha Parker, their sixteen-year-old adopted daughter, Mary Ann Markham, and her best friend, Jennifer Martin, think when they visit a hilltop in the western part of Mercer County that contains a Christmas tree farm; an old, apparently abandoned mansion; and... a corpse. If that isn't bad enough, after reporting the corpse to Jennifer's uncle, Sheriff's Deputy J.J. McClure, the girls decide they want to disregard the "No Trespassing" sign and explore the mansion's interior—several times.
As usual, they discover more dead bodies. Add to that a couple of kidnappings and a cache of smuggled goods, and they're lucky to escape with their lives before they finally discover the real murderer at a most unexpected location.