New Kid begins with Jordan Banks, a 12-year-old Black boy, sitting with his parents in their living room in Washington Heights, Manhattan. Jordan draws in his sketchbook while his mother looks at the website of Riverdale Academy Day School (RAD), the elite private school where she has enrolled him. Jordan's father knows Jordan isn't excited about the new school, which appears on its website to lack diversity, and would prefer to go to art school, but Jordan's mother refuses to hear any complaints.
Jordan drives to school with Liam Landers and Liam's father, a wealthy white businessman. The school has assigned Liam to be Jordan's guide. The first thing Jordan notices is that most students at RAD are white or Asian, with only a few Black students per grade. Jordan's first week at RAD is full of loneliness and a sense that he is lost. He notices the ignorance of white teachers who confuse Black students with each other, as well as the deliberate provocations of Andy, a white attention-seeker who makes racist insinuations about students of color.
Over the fall semester, Jordan develops a friendship with Liam, with whom he plays Xbox Live. He eventually speaks with Drew, the other Black student in his homeroom class, and the two bond over their frustration at the constant microaggressions they have to put up with. When the homeroom teacher hears Drew jokingly call Jordan "dawg," she misunderstands the irony of the in-joke, prompting Drew to call her out for always confusing him for another Black student named Deandre. At home, Jordan's parents get into an argument over the pressure Jordan's mother is putting on Jordan to assimilate into the culture of a white-dominated and elite place like RAD as preparation for life as a Black person in corporate America.
After talking with his grandfather, Jordan brings Liam and Drew together by having them all play Xbox Live campaigns together. At school, they also make an effort not to shun Alexandra, a socially awkward and friendless girl who wears a sock puppet on her hand. Before Christmas, the students browse books at the school book fair. Jordan and Drew bond over the lack of reading material to interest them: everything targeted at Black boys their age tells a gritty tale of urban survival and fatherlessness.
Over the Christmas break, Jordan reconnects with Kirk, his oldest friend. They are both relieved that Jordan's new life as a private school student hasn't impeded their ability to relate to one another. Jordan also goes for the first time to Liam's family's mansion. He agrees not to judge Liam for being so wealthy, for which Liam is grateful. He gives Jordan NBA2K Deluxe for Christmas, a better edition of the game Jordan's parents get him as a rare splurge for them.
In the new semester, Jordan is resistant to his art class, which is taught by a woman who shows off her own abstract paintings within the classroom. He prefers figuration. One day after school, Alexandra reveals that she wears a sock puppet on her hand because she has a scar from the time she saved her little brother from a falling pot of boiling water. She shows Jordan, who is surprised to see the scar is almost nothing. She says he can tell only one other person the truth about her hand.
During lunch in the cafeteria, Drew snaps at Andy when Andy tries to provoke Ramon by asking about his mother cooking Mexican food. The insults fly back and forth until Andy shoves Drew, prompting Drew to shove him back. Andy falls, slipping on his own apple, and their homeroom teacher comes to punish Drew. Having had enough of students of color like Drew being judged more harshly, Jordan speaks up, telling the truth of what happened; this leads the way for others to support Drew, including other teachers. The compromise is that the students have to clean up the mess made when Andy's tray was dropped.
On the bus home that day, Jordan realizes he doesn't have his sketchbook. The next day he goes to class early and finds his homeroom teacher reading it. She fixates on the comics he has written about the microaggressions he has witnessed and experienced at RAD. She confronts him about his "anger" and tries to convince him to assimilate into the school culture. He tells her he is sick of feeling different all the time, and challenges her to think about how she would like coming to his neighborhood—where she would stand out as different—to teach.
As the semester goes on, Jordan seeks to lessen Alexandra's burden by telling her secret to the most notorious gossip in their year. Soon everyone knows about her burn and that it isn't a big deal, so Alexandra can stop wearing her puppet. She is thankful to Jordan for trying to help her. In art class, Jordan sees that his teacher also paints figuratively. She convinces him to paint something abstract: as he does, he thinks about all the frustrations of life at RAD. His teacher is so impressed with his painting that she ends up surprising him by making it the cover of the yearbook.
On the last day of school, after weeks of studying and exams, everyone compliments Jordan's work as they sign yearbooks and wish each other a good summer. Jordan makes plans to see Drew and Liam over the break. When his parents come to pick him up, they comment on how Jordan seems like a "new kid," noticing that he is more well-adjusted and content, even if RAD has been a mixed bag for him. The graphic novel ends with Jordan going to play basketball with his neighborhood friends. He expresses gratitude for them by saying that friends are like training wheels because they keep you from falling down—a "metaphor," which is something he learned in English class. They affectionately tease him for not knowing the difference between a metaphor and a simile.
