What is the theme in Joe Turner's Come and Gone by August Wilson?

The primary theme in the play is the search for identity. Although Herald Loomis believes he is searching for his lost wife, Martha, the African conjurer, Bynum, lets him know that Herald is really searching for his song or identity. Herald has forgotten his song as a result of his seven-year enslavement by Joe Turner, a notorious Tennessee plantation owner that illegally enslaved free African Americans to work for him. Bynum tells Herald that Turner captured him, not just to work on his plantation, but to try to steal Herald's song.