Leslie and Crow return to their space station after an exploration of lunar ice caves. Upon arrival Crow dies of an unexplained fungus. Faith, the station's biochemist, analyzes the material. After the ship's doctor, Dobson, contracts the infection, he unites with Leslie in telling
commander Garland that Earth must be notified. But Garland doesn't want the mission to be disrupted and refuses their request. They go over his head and attempt contact with Earth but are foiled by Curran, the ship's communication officer, who's in love with Garland. The space station runs into a
meteor shower which tears a hole in the station's side, causing the mysterious fungus to esc...