The thirteen-year-old boy Adam Harrison is not much different from his peers. Only the hair on his head is extremely thick and grows very quickly. Because of this, as described in the film "Become a legend! Bigfoot the Younger", some classmates scoff at him. Once in the basement of his house, Adam finds a mysterious box of letters. The boy's mother always said that his father was killed. It turns out he is alive and sometimes sends family messages. Dad lives on the lost track number 89, which is in the mountains covered with dense forest. Adam decided to find the missing parent. He finds it in a fantastic valley in the middle of the mountains, where hundred-year-old trees grow. It turns out the boy's father is the legendary Yeti Snowman. Bigfoot hides from the pharmaceutical company "HairCo (Hair Corporation)." They want to get the DNA of the forest keeper. The ultimate goal of these greedy businessmen is to develop a hair growth stimulant. Adam remains with his father. He develops his abilities - to understand the language of animals, to treat with the touch of hands and much more. True, the boy is now in danger, too, but he has the right friends - squirrels, a giant bear, chatterer and a raccoon.