A young African American woman doing primate research in Congo tries to rescue a baby bonobo whose parents have been killed by rebel soldiers for bush meat, but he doesn’t survive.
Later, her son Ben skips a grade and enters middle school as a brainy though socially awkward preadolescent. He makes friends with a gregarious Chinese American kid named Bao. Hitting puberty, he takes dance lessons and learns martial arts, but some of his encounters with girls and boys prove embarrassing, even traumatic. Smart, sensitive, and frequently thinking about sex, he identifies with the bonobos his mother used to study.
Ben’s father has an affair, and his parents split up. When he, Bao, and another friend dress up in gorilla suits, go trick-or-treating, and crash his father's Halloween party, Ben acts out his anger and alienation by "going ape.”
In college, Ben studies hard, joins a fraternity at Bao’s urging, and has a romantic relationship with a young woman. During Hell Week, the fraternity brothers demonstrate male human behavior at its worst.
Another young woman claims to have been raped in the basement of the fraternity house. Circumstantial evidence points to Ben. His girlfriend turns against him, but his mom’s early mentor shows up as an expert witness for the defense. He defends Ben and the bonobos Ben identifies with as sensitive, peaceful creatures, less aggressive than chimps and humans. A plea bargain lands Ben in a highly ironic position between humans and their primate cousins. His girlfriend reconsiders—and signals a willingness to reconnect.