Xiao Ming "Bernard" Chang is a band geek and a sophomore in high school who feels pulled towards the world of basketball, despite his rivalry with his former friend, star player Matt O'Neil. As circumstances unfold, he crosses paths with his new bandmate, Kristy, and finds himself instantly captivated by her. However, this newfound interest quickly turns sour when Matt begins to flirt with Kristy, igniting a fierce competition between the two.
After a humiliating incident at a party where his friends lock him in the basement, Chang confronts Matt about a past basketball game and boldly claims he can dunk. The competition escalates when Matt mocks him, leading to an embarrassing fall into a swimming pool, intensifying Chang's determination to prove himself. With the weight of his mother Chen's critical gaze upon him, Chang is driven to reinvent himself.
In a moment of bravery, Chang bets Matt that he can achieve a dunk by the time of the homecoming event. The stakes are high: if Chang wins, Matt must shave his head and hand over his prized Kobe Bryant jersey; if he loses, Chang will do the same and forfeit his cherished 1st edition Pokémon Trading Card. Kristy, aware of the bet's deeper implications, chooses to support him unconditionally. With the help of his loyal friend Bo, Chang embarks on rigorous training, but soon feels discouraged by his progress.
In search of guidance, Chang discovers YouTuber Deandre Cooke, known for his impressive dunking skills. Upon meeting Deandre, Chang persuades him to coach him, while Bo offers to enhance the quality of Deandre’s video content in lieu of payment. Their collaboration leads to significant improvements in Chang’s performance, and they develop a strong bond during their time together.
However, as fame begins to encircle Chang, tensions rise between him and his mother, and their relationship shows signs of strain. The night before the dunk challenge, Chang feels unprepared and sneaks into school for some last-minute practice. When the big day arrives, the atmosphere is electric as Chang successfully completes the dunk, thereby winning the bet and gaining new recognition among his peers.
Despite the exhilarating success, Chen remains oblivious to Chang's achievements. An invitation from ESPN to discuss his dunking victory takes him to New York, where his bravado is tested when he attempts to recreate his dunk but fails. As accusations of cheating arise, tensions burst between him and Matt, culminating in both boys being suspended from school. During this tumultuous time, Chang and his mother finally confront their issues; she reassures him that he doesn’t need to seek validation from others, while Chang expresses his frustration over her perpetual unhappiness.
Realizing her son's potential, Chen reflects on her own behavior and seeks to mend their bond by tackling remnants of their past together. As Chang reconnects with Bo and Kristy, evolving their relationship into romance, he also reconciles with Matt, leading to personal growth all around.
In a climactic moment filled with hope, Chang now thrives as a member of the basketball team. When the coach calls for him to enter the game, Chang rises to the challenge. Although he falters momentarily, he manages to steal the ball from an opponent, dashing down the court to take a leap for the dunk as the crowd erupts in cheers, leaving his journey open for continued triumphs.
