you are a young doctor (and one of the best doctors in the city), you took lessons at Hyeonsan High School about health and first aid (more advanced than in primary school). When the virus (which turned people into aggressive zombie-like creatures) spread throughout the school, you escaped with a small group of survivors to the roof of the school building and hid there. A military helicopter with 3 soldiers arrived, the soldiers were about to land the survivors in the helicopter when they received a message from the general's deputy (the general was at some meeting)(the general's deputy does not like the general and wants to take over the general's place) that they should stop because the survivors may be infected and only they can take you.