Host, Mo., is a quiet ranching community where everyone knows everyone else, and almost everybody earns their living from a local meat-products packager, Host Tender Meats. New to town is veterinarian Eli Rudkus, who makes Host his home after his predecessor retires, leaving a professional vacancy that Eli is happy to fill. However, when Eli is called to the ranch of Jacob Long, a local cattleman, the young veterinarian's seemingly routine house call exposes a dangerous secret about Host Tender Meats that could annihilate this small town. Eli's efforts to warn the town are thwarted by Fletcher Odermatt, the owner of Host Tender Meats. Odermatt is willing to go to any lengths to keep his company's dark secret buried. To that end, he enlists cutthroat attorney Hayley Anderson to smear Eli's reputation. Before long, though, Eli and Jocob convince Hayley that what started as a small "parasite problem" is now a disaster on the verge of becoming too large to contain. As catastrophe looms, the trio races against time, nature and science to save their town — and perhaps the world.