Let'em Breathe Space by Lester del Rey
The old space freighter Wahoo is all Dr. Pietro can afford for his expedition to the rings of Saturn. Although built for a crew of 6 the good doctor crams 19 people into the Wahoo, and after 5 months they are really getting on each other’s nerves. Then someone starts killing people and poisoning the air giving plants in the hydroponics bay. Can our hero Paul Tremaine find the killer before he suffocates? Perhaps you should hold your breath. – Let’em Breathe Space was first published in the July 1953 edition of Space Science Fiction magazine.
