After Zheng Yu returned home from vacation, he was invited by Liu Yang to attend a birthday party. After attending the appointment, he met Liu Yang's four classmates Chen Yanyan, Zhou Chi, Qin Ye, and Fang Yiming. During the party, Liu Yang never showed up, which aroused everyone's suspicion. Zheng Yu found a black figure holding an ax on the second floor. He informed everyone but was questioned. Later, everyone found Liu Yang's "body" and fell into the dilemma of a secret room with locked doors and windows and blocked signals. As notes such as "You will all die" and "The murderer is among the five of you" appeared, everyone suspected that the murderer was in the room.
