Su Wan, a transfer student in high school, gets to know Lu Yang, the “cool academic genius,” after they accidentally swap notes. A window seat in the library, takeout with the cilantro left out, and the sight of him giving up his place in a race to carry her all help their young love blossom beneath the plane trees. Her best friend, Lin Xi, records every flutter of their hearts, while Lu Yang’s childhood friend, Chen Yu, works hard to play matchmaker. They expect to face the future together after the college entrance exams, but Lu Yang comes down with sudden gastroenteritis and underperforms, getting into a second-tier university in the same city as Su Wan. The two promise that “distance won’t separate our hearts.”
At university, Su Wan attends a top school and attracts the attention of an older student. Lu Yang quietly wins her heart back through competition awards and late-night equipment repairs. Lin Xi pursues her dream of screenwriting, facing rejection after rejection but refusing to give up, while Chen Yu falls in love with the top student Zhao Xiaoman through esports. But just before graduation, Su Wan’s parents force her to study in the UK. She can only part from Lu Yang in tears, leaving him a peace charm that carries their promise.
From then on, Lu Yang falls into a slump: he fails his graduate school entrance exams and struggles through one difficult job after another. Chen Yu stays by his side through the low point, while Su Wan works tirelessly to grow abroad and Lin Xi turns their story into a screenplay. Three years later, Su Wan returns to China with a wealth of talent, just as Lu Yang hits a roadblock with his startup. She mortgages her apartment to help him through the crisis and uses her connections in media to clear his path. Jiang Zhe also offers a helping hand as a partner.
In the end, Lu Yang’s company gets back on track, and he proposes to Su Wan at the celebratory banquet. They hold their wedding beneath the same plane tree, with Teacher Zhang officiating. Lin Xi’s screenplay has become a hit series, and Chen Yu’s esports club wins a championship. In the summer night breeze, Su Wan leans against Lu Yang’s shoulder, surrounded by friends whose stories have all found happy endings. After crossing mountains and seas, their love finally ripens, through devotion and redemption, into the warmest echo of youth.
