Garam hides a dark sexual secret she doesn’t want anyone to find out: her body only reacts when she’s being dominated. But one day, this secret is discovered by her younger brother’s friend, Ha-seong. 'Want me to help you? Then open your mouth.' Thus begins Garam’s sexual relationship with Ha-seong. But things get complicated when Ha-seong's younger brother, Woo-jae, also wants to join them. Surrounded by younger men, Garam finds herself caught in a forbidden love triangle.