Medical student Shangguan Qingyun clashes with his advisor, Zhou Hongliang, over a poor evaluation of his internship report. Late one night, he goes online and encounters a ghost calling itself "Believe." It knows personal details about him and offers him "guidance." In truth, "Believe" is part of a scheme: Zhang Zhiyi, who has a secret crush on Shen Yu, conspires with it to manipulate five people, Shangguan, Zhou Hongliang, Shen Yu, Chen Bing, and Zhang Zhiyi, all born on the same day of a leap month. They use the ritual known as "Four Leap Months to Return the Soul" to control them. Shangguan believes "Believe" and tries to harm Zhou Hongliang, but accidentally injures Zhang Zhiyi instead. Chen Bing gets dragged into the affair while trying to catch up with Shangguan. In the end, Zhou Hongliang falls to his death, Shangguan "takes his own life," and Chen Bing is killed. After coming to his senses, Zhang Zhiyi uses a cigarette soaked in the three victims' blood to defeat "Believe." Everyone comes back to life, but they forget him. Only Chen Bing is willing to get to know him again.
