Director Choi's briefing about the mission leaves Song Ji-an displeased. Reaching the research station alone proves no easy feat for the crew.

Racing against time as the research station falls under destruction, the surviving crew members decide on the fate of the mission — and their own.

The crew's initial findings are at odds with their knowledge of the research station. Split into threes, the members set out to look for the sample.

Ji-an's body cam captures a startling moment of life and death. Submerged in sweat, Gong Soo-chan shows worrisome signs of an unusual infection.

E2, Ryu Tae-suk and the samples go missing. Seeing a familiar name on the intruder, Ji-an follows her down the vents for answers.

Han Yun-jae updates the director and gets access to a restricted area. The crew learns of the sample's powers and the true motive behind their mission.

Recalling her sister's encrypted message, Ji-an searches the database for Luna. A young intruder and a double-crosser emerge from the shadows.

Ji-an opens a hard drive that chronicles Song Won-kyung's life and work on the station. Meanwhile, others uncover the remains of the experiment.