Sisters Ronnie and Rita love sitting in their front porch rockers, observing life in bucolic Castleton. They love mysteries, and like their favorite detective Miss Marple, they "solve" the problems and mysteries of the town. Their amateur sleuth skills are called upon when a developer begins buying up the town's precious green spaces to build an upscale community. The prime target is the local dairy. The owner refuses to sell, but a sudden listeria outbreak that turns deadly may force him to do so. Was the outbreak a natural occurrence, or was it a nefariously planned scheme? A local reporter investigating the outbreak is killed in a hit and run. Signs point to murder. What secrets had he uncovered? With no time to cry over spilt milk, Ronnie and Rita race to unmask the killer. But can they discover the mastermind before more people die?