Set in a future where people peacefully coexist in a sealed bubble, they are divided into four levels — Alpha, Beta, Gamma, and deviants unable to conform. Elizabeth hails from a Beta family and her father seeks to pair her off with Bindon, a civil servant with prospects. Elizabeth, however, is in love with Jon, a modest rocket pad official. When Elizabeth's father decides to have her mind altered to remove feelings for Jon, the lovers flee, discovering fresh air and the beauty and cruelness of nature for the first time.