The first step in summarizing the main conflict in a book is identifying it. While not all books have a central conflict, most drama and fiction have plot arcs that begin with a conflict and end with its resolution.
Start by determining which character in the book is the protagonist or main character. The main conflict in a book is normally a conflict in which the main character is involved. Next, think about whether the conflict is internal (some sort of psychological conflict) or external (with one or more antagonists).
To write a summary, first you should give a short description of the protagonist. Next identify whether the conflict is internal (for example, someone struggling to decide on a career or make a moral choice) or external (against some sort of antagonist). Next describe the basic situation of the conflict as it appears at the beginning of the story. Conclude by describing how the conflict is resolved.