Ching, Marf Yau, a secondary school girl who struggles with a stutter, starts selling the lingerie she wears online to earn extra pocket money, spurred by her best friend, Rachel Sheena Chan. As a steady stream of regular patrons appears, Ching enjoys the compliments and finds herself chatting with them more often than before. Following Rachel’s suggestion, they decide to grow the operation by creating a fake account that pretends to be a flight attendant, discovering that these items can fetch several thousand dollars online. Some patrons request face-to-face meetings as well, complicating matters further. During her first in-person encounter, Ching starts her period and tries to cancel, but the patron pressures her to proceed, insisting on buying the stained pants, and her stutter prevents her from saying no. Even though the patron pays an extra thousand dollars, the experience leaves Ching frightened and deepens her anxiety about her stutter.
Ching then grows closer to another patron, drawn in by their conversations and his appealing social-media presence. She learns his real identity as Gabriel Lau, a university physics professor, and begins skipping classes to attend his lectures. She becomes increasingly attracted to him, captivated by his humorous teaching style, but soon discovers he is married. Despite this, Lau continues to propose face-to-face meetings while they chat online. After talking it over with Rachel, Ching agrees to meet him, but her concerns about her stuttering resurface just before the planned transaction. Eventually, she asks Rachel to meet Lau in her place while she observes from a distance. The meetup goes well, and Lau exchanges contact information with Rachel. They start chatting regularly and meet up to trade lingerie. After witnessing Lau treat Rachel to lunch at a hotel, Ching feels jealous. She bakes a cake and tries to find Lau at the university, but cannot bring herself to present herself again. Lau awkwardly accepts the cake but quickly tries to leave, finding her presence strange. In a impulsive move, Ching pulls out her worn lingerie and tries to gift them to Lau, provoking a furious outburst in him as he hurls the cake and the pants to the ground.
Hurt by his reaction, Ching seeks revenge by posting photos of Lau and Rachel’s meetups along with their chat records about selling lingerie on an online forum. The post triggers a backlash, exposing Lau’s personal information and severely damaging his reputation. Lau desperately calls Rachel, asking why she betrayed him, only to learn that she has also been victimized. Rachel confronts Ching, and their friendship comes to an end. In retaliation, Lau prints Rachel’s photos with defamatory slogans and displays them near her school. The next morning, the school hall fills with students as the discipline master orders a bag check to identify those involved. Because of Ching’s stutter, classmates seize the opportunity to exploit her difficulty in refusing and hide lingerie in bags with forbidden colors or patterns. The search yields no concrete results, but the discipline master recognizes Rachel and confronts her. In a moment of distraction, Ching rushes out of the hall and dumps her schoolbag, full of pants, onto the playground, then laughs and slowly reconciles with Rachel.
