abstract: a summary of a text, scientific article, document, speech, etc.; epitome. (Random House Dictionary)
While an abstract and a summary serve much the same function, it is the convention to use the term "summary" when speaking of a summarization of a work of literature.
eNotes provides a summary of Mama and can be access through the link I have inserted below and embedded with a hyperlink on the word "Mama."
Mama tells the story of Mildred Peacock who is an uneducated black woman in the 1960s, whose story of violence and abuse is told through her point of view alternating with her daughter's point of view.