After the disappearance of celestial bodies, only those on orbital stations and ships survive. Decades after the devastation, on a lifeless moon they discover an unusual sea of blood, and an expedition is quickly sent there in search of vital resources. To explore the depths, they build a submarine and imprison a convicted criminal inside, who will have a chance at freedom if they succeed. But due to pressure and harsh conditions, he must move blindly, not knowing what lies beneath. This is already the thirteenth attempt, and the previous expeditions did not return.