the girl ma yufeng (played by ma sichen) was sentenced to half a year in prison for drug hiding. her boyfriend robert instructed her to find the woman who killed his elder brother in prison. Winnie， in order to avenge his elder brother. yufeng, who was imprisoned for the first time, began a prison life called the "first cocoon". the female prisoner in the same cell, "man mother", bullying newcomers with a domineering personality. yufeng was fortunately rescued by the famous "crazy sister" (played by wu jiali) in prison when she was beaten by the man. since then, yufeng has become friends with the crazy sister and the talkative and optimistic big belly (played by lin jianming). it turns out that crazy sister is Winnie，Winnie being dragged down by his drug-taking father, he had to survive in the fun. he became addicted to drugs because of a chance encounter. Winnie ayong (played by andy lau), got to know her undercover policeman ayong (played by andy lau), and the two fell in love. ayong was addicted to drugs. Winnie he never left him and planned to live with him in canada, but unexpectedly, ayong's identity was revealed, which led to Winnie kill robert's elder brother... aaa