Parasitology doctoral student Song Yiqing returns through rebirth. In her past life, roommate Zhang Meimei ate a BSL-2 experimental chicken, causing 7 infections; she suffered cyberbullying, her parents committed suicide, and she jumped from a building. In this life, she keeps evidence, calls the police, isolates Zhang Meimei and others, and develops ultrasonic inactivation technology to prevent the epidemic. Three years later she becomes a national-level expert with an annual salary of 3.5 million; Zhang Meimei is disabled and reduced to a cleaning lady. She tears up the plea letter and turns away.