In Chapter 3 of "The Call of the Wild" by Jack London, the climax is reached when Buck, the main character, experiences his first taste of primitive instincts and freedom. Buck is purchased by a prospector named Thornton, who treats him kindly and gains his loyalty. One day, while exploring in the wilderness, Buck encounters a large bull moose. His ancestral instincts kick in, and he attacks and kills the moose single-handedly, proving his strength and ultimately embracing his primal nature. This moment of triumph marks a turning point in Buck's journey, as he fully embraces his wild, instinctual side and becomes less reliant on his domesticated past.
