Aristotle expounds in his Poetics the function of “reversal” in producing twists and turns of drama plot. The expounding is however confined to its formal function. In the tragicomedy “A Raisin in the Sun”, the playwright Lorraine Hansberry breaks through the confinement and employs creatively “reversal” as a link to connect the “explicit” plot with the “implicit” cultural context. Hansberry uses the main characters’ reversal of fate in the explicit plot to bring forth the value narrative in the implicit cultural context. Reversal urges the characters to forsake the values of white oppressors and to reclaim the root of African American culture so that they are on the right track to construct their racial cultural identity.