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

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.

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

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.

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.

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