Sae-bom finally gets to be a homeowner. At the end of all her hard work, she thought happiness was just around the corner. However, she ends up learning she might have caught a new contagion, one that causes the infected to bite people after losing their minds. Even though Sae-bom and Seung-young are under an oath of secrecy, reporters approach them with a hefty sum of money. Meanwhile, Yi-hyun and Tae-seok from the Central Disaster Countermeasures Headquarters (CDCH) join forces to find out the true nature of the disease.