When the infected outside the wall began to show unusual intelligence and organization, Li Qian was ordered to lead a team to venture into the infected old city area to investigate possible new mutations of the virus. During her exploration, she accidentally discovers her father, who is still alive but partially infected. Dr. Li Zhenhua reveals the terrible truth about the virus - it is not simply destroying human beings, but reshaping life forms and creating some kind of collective consciousness network.
The team was forced to go deep into the most dangerous "Laboratory Zero" - the origin of the virus outbreak, and found that the infected had established a complex biotech society and were controlled by a super consciousness called the "Master Brain". In the final showdown, they face a difficult choice: destroying the mastermind network may liberate the infected, but it may also unleash more terrifying consequences; and doing nothing means the inevitable fall of the last bastion of mankind.
