When the most popular couples of Seoul's American High break up three weeks before prom, Irene doesn't have anyone to go with. Her best friend Seulgi gives her a bet to make the weird kid who transferred to Seoul American High; Jung Hoseok from their maths class to make him famous enough to make him the prom king. As she thought she'd only make him famous enough to make him the prom king, she starts catching feelings for him. Her best friend then later tells him about their bet to hoseok before prom, and.... things get really messy.