Ivan Marx, a fifty-five-year-old tracker and outdoorsman, has been hunting the legendary Bigfoot for more than ten years. Ivan is one of the last “mountain men” and various governmental agencies hire him to track “renegade” predatory animals that kill “innocent” animals. In the 1950s, he was called to Kodiak, Alaska, to see if a bear was killing local cattle, but his investigation concluded that the cows were dying of malnutrition due to inferior quality grassland and the bears were feeding on the corpses. One rancher, however, insisted his cattle were being killed by “Bigfoot.” Ivan’s brother-in-law sends him to the Petrified Forest National Park in Arizona to look at 700-year-old petroglyphs that depict a biped with large hands and feet. According to a Native American legend, these creatures kidnapped babies and the tribe moved away in fear. Later, in the mountains, Ivan discovers giant human-like footprints that could only belong to a five hundred pound animal. He also finds hair that he claims does not match any known animal. Ivan is later hired to track a renegade bear in the mountains and finds it dead with a broken neck. After finding a large “Bigfoot” print near the body, Ivan is convinced the creature is real and posts advertisements to seek information from other believers. Most photographs and stories seem fraudulent, but Ivan thinks four images are real: they show a large biped with a domed scalp and glowing red eyes. On another mountain hunt, Ivan spots his first “Bigfoot,” but when he brings witnesses to look at the creature’s fresh tracks, the rain has washed them away. Feeling that he was chosen to prove the existence of Bigfoot, Ivan hunts for the creature in the Rocky Mountains, the Redwood forests, and the Washington State coastline. After running out of money, Ivan takes a job photographing bears outside Bossburg, Washington. When he finds more “Bigfoot” tracks, he follows them and finally gets a picture of the creature, but he is dismayed when the “experts” refuse to believe his photographic evidence. Ivan wonders if “Bigfoots” are migratory animals and plots past “Bigfoot” sightings, surmising the creatures travel north in the summer to the Artic Circle. He puts together a team and heads north, where he finds fossil footprints in old lava flows and listens to Inuit folklore. One story claims that the creatures bring humans who died on the tundra to the edge of towns for burial, leading Ivan to speculate that the Bigfoots carry their dead thousands of miles to bury them in glacial crevices. As the summer comes to an end, Ivan hires a small airplane and spots a Bigfoot by a river, but by the time he lands the creature is gone. Since Bigfoots are always near water, Ivan wonders if the creatures eat fish, vegetation or meat? As Ivan heads south with the caribou to determine Bigfoot’s food source, he does not spot the creature and decides Bigfoots are vegetarians with perhaps some fish in their diet. Ivan posits that a place called “Beaver Swamp” is where Bigfoots will be in the spring. As the snow thaws, he tracks Bigfoot and builds a hunter’s blind. After weeks of waiting, Ivan spots two Bigfoots; an adult and child. He films them eating swamp grass, but as the creatures are hundreds of yards away, no details can be seen on Ivan’s film. As the Bigfoots leave, Ivan wonders how long they can survive the onslaught of man and reaffirms his mission to find more information on them.