In school, Wang Hsiao-hsia and her childhood friend Yuzu are seen as a couple, but Hsiao-hsia secretly longs for the transfer student Cheng Yih. Cheng Yih, admired for his exceptional grades, talent, and fighting skills, captivates her heart. Despite her poor academic performance, Hsiao-hsia tries various methods to win his affection, but nothing works. Unbeknownst to her, Cheng Yih harbors feelings for Hsiao-hsia as well. Meanwhile, Yuzu, fiercely protective of Hsiao-hsia, is wary of anyone trying to get close to her. As summer arrives, a fragrant first love begins to bloom among the three of them, reminiscent of lemongrass.

六（郑人硕 饰）是位靠贩售爱心商品维生的身障人士，生活大小事都需倚赖父亲（喜翔 饰）帮忙，从未谈过恋爱的他，对于性有着无限的憧憬与幻想，在大楼保全文哥（郑志伟 饰）的引介下，六认识了一个沉默的少女泡面（邱偲琹 饰），长年生活在阴暗狭小文具店的她，不仅要照顾有心理疾病的母亲（黄采仪 饰），在学校也备受同侪霸凌。对未来不抱期待的泡面，与六从平淡的性交易关系，逐渐发展出一段刻骨铭心的爱情，同时六也发现文哥与泡面似乎也有着不寻常的关系…同样生活在灰色角落的他们，透过相遇的微光温热了彼此的心，因慾望点燃了希望，两人最终能否走出生命的困境…