The plot of a story (regardless of the type of story) is the writer's purpose behind the telling of a story. What this means is what is the story (what is it about).
Elie Wiesel's novel Night is a sort of autobiography regarding Elie's time in the concentration camps during the Holocaust. Elie's tale is one which describes the horrors he faced as a young Jewish boy. The novel is written as a recollection of what Elie faced as a Jewish person in a concentration camp, the loss of his family, and the loss of his faith.
Elie's purpose behind the telling of his tragic story is one meant to enlighten readers about the trials and tribulations the Jewish people faced during World War II and the Holocaust. What Elie wants readers to know is the truth behind the treatment of the Jewish people during this time. Therefore, the plot of the story is to enlighten and educate readers about the Holocaust, what really happened in the concentration camps, and what he had to do in order to survive.