The action takes place in the late 1940s. A large-scale land-surveying research is underway in a remote area of Eastern Siberia. The work had almost been concluded when a wire arrives with the news of people disappearing in the locality of Yambuy. The expedition’s chief and radioman decide to go in search of the lost ones. The local Evenk hunters come to their aid. Many dangerous adventures lie in store for these daring people before they find the culprit – a man-eating bear.

On one of his trips through the nature reserve, the ranger Michailytsch found a young lynx whose mother was killed by a bear. He takes it with him to his log cabin and calls it Kunak, which means friend. The young lynx gets used to the human environment. He grows up to become a stately lynx. When he attacks a rooster one day, he is sent away. On his wanderings through the Siberian forest, he is caught in a poacher’s trap. Only after a long search does Michailytsch find Kunak and frees him. But the lynx came to the attention of thieves who catch it and sell it to a circus in the city…