We are midway through the 26th Century, out at the edge of Human space, in the Teegarden system.
John B, a humble repairman and "former human" (having lost his legal status as such), has left the Earth for mysterious reasons. He is perhaps the unluckiest being in the galaxy.
He has wound up at the Human Exchange Concourse, or the "HEC," once the site of Humanity's First Galactic Fair. It was the biggest flop in Human history. "The Fairgrounds" is perhaps the unluckiest place in Human space. You don't go there, you end up there.
John's luck seems to have changed when he gets a good apartment at an amazingly reasonable price only to find his roommate is Althaar, an Iltorian, who is determined to befriend a Human (Iltorians are the kindest, nicest species in all known space, and natural diplomats, beloved by almost all, but their slightest presence causes Humans to instinctively respond with panic, fear, disgust, nausea, and loss of bodily functions).
Can a Human and Iltorian live together without one of them driving the other crazy?