The protagonist of Caucasian Chalk Circle is Grusha, a peasant girl who is accidentally left with the baby Michael when his father is killed in a coup and who raises him as her own. The play is loosely based on The Chalk Circle by Li Qianfu and even more loosely based on the biblical Judgment of Solomon. In both cases it is the character of Grusha who is the most significant innovation, since in the biblical story, the mother is an entirely flat character, and in the Chinese play, she is a prostitute with quite a different life story.

In both sources, the girl is the baby's natural mother. Grusha, however, is simply a better and more conscientious mother than Natella, Michael's birth mother. This is revealed when she refuses to harm Michael by pulling him out of the chalk circle. Even the absurd and corrupt judge, Azdak, is able to see that Grusha loves Michael more than Natella and gives him to her regardless of his actual parentage.