What is the theme in Last of the Breed by Louis L'Amour?

Love and hate is a recurring idea in the story. Mack loves his country and his people, the American Indians, and when he is captured, he feels this is not just an attack against his country, but also on him personally. The fact of being raised with the same values and traditions of his Indian ancestors, Mack feels the need to make Zamatev and Alekhin pay for the disrespect they have shown him. It was both his love of his country and his pride in his people that made him hate Zamatev and Alekhin. Mack is determined that if he does not kill them before he escapes from Siberia, he will return to kill both of them.