A routine disaster thriller--a biochemical spill threatens Yellowstone National Park--distinguished by a clean, literate prose style and some magnificent scenery. The narrative opens with the villain, known simply as Skanz, doing what he does best--tracking and killing. Skanz's current quarry is a disgruntled scientist of PetroDyne, the biochemical- arms manufacturer that employs Skanz as a roving hit-man. The scientist dies warning Skanz, ``You don't know what I've arranged''--but Skanz finds out after a truckload of one of PetroDyne's most toxic illegal products, a ``hemorrhagic fever derivative,'' is stolen, then accidentally driven over a Yellowstone cliff. Near the cliff is working-class hero Jack Fairchild, a park ranger whose laid-back manner and love of the land make him a pointed foil for Skanz and the murderous, fascist- like force that PetroDyne's amoral chief, with approval from Washington, sends into Yellowstone to contain knowledge of the spill and of its horrid effects--which include sending its victims, both human and animal, into a homicidal rage as blood boils out of their pores. With a vigorously described Yellowstone as a backdrop, the novel's second, swifter half details Skanz's violent pursuit of Fairchild and the band he gathers round him--including the driver of the stolen truck, the local medical officer, Fairchild's new girlfriend, and his old Indian buddy, Isaac. As the carnage intensifies, bodies fall to the ground like pine cones, with a fever-maddened mountain cat adding to the count: Will Fairchild and friends make it to freedom? A smoothly written debut novel, but stock if well-drawn characters (the noble Indian, the robber-baron industrialist) and an overbearing moralism (free spirit vs. Big Business) drag on the action, which ends in corn (``It was a big, big country. They walked out into the cool dark, together'').