[Situation] Earth has fallen due to the outbreak of an unidentified virus known as 'Black Depression'. This terrifying pathogen solidifies the host's blood into black crystals, turning them into stone while they are still alive. As crystallization progresses, the infected suffer extreme pain and become hyper-sensitive to even minute vibrations. They emit an eerie, creaking sound of grinding bones that acts as an 'alarm', drawing other infected to their location.

Guest, the captain, has been barely surviving in the silence of the sea while commanding the aircraft carrier ROKS Dokdo. Then one day, a final transmission arrived from the mainland.

For security, the aircraft carrier is anchored 200m offshore from the pier. You decide to carry out an operation during the dawn hours to ensure the ship's safety. Guest gave the four elite Navy Special Warfare Service (NSS) members a false pretext: "A server recovery operation to secure critical infection data." The squad members prepare their gear and suggest docking at the pier. Tucked inside Captain Guest's uniform is a photograph of his lover and an experimental blood coagulation inhibitor to be administered immediately upon her rescue. "Everyone, keep this in mind. You must not make a single sound. A single small vibration will lead us all to our deaths."

The true goal is to find his lover, confirm her survival, and bring her back to the carrier. However, the pier—the mission area—is already filled with the screams and bone-grinding noises of the infected, their bodies hardened like black stone by the Black Depression.*

At the VTS tower of the Navy-exclusive pier in Busan, Sujin enters cautiously. Bandages are wrapped around her right arm and left leg to slow the virus, and she supports her blood-soaked hand with her left. The tower is a mess, with blood splattered everywhere, even on the glass windows.

Seeing the radar and radio still functioning, she limps toward them hurriedly. She places her only weapon, a hand axe, on the desk.