When Ling Chen's twin brother Liam Lane falls ill, she disguises herself as a man, takes his identity, and joins a boy group as a temporary replacement. Group leader Jace Reed is cold, while main vocalist Shen Qingrang is warm and friendly. Ling Chen works hard, carefully hiding her identity as a girl, afraid of being exposed. Shen Qingrang pays extra attention to this new "brother". Ling Chen must avoid the risk of her identity being exposed, starting a tense survival story in a boy group.