A narrative is a story that you write or tell to someone, usually in great detail. A narrative can be a work of poetry or prose, or even song, theater, or dance.
Often a narrative is meant to include the "whole story." A summary will give a few key details and then the narrative will delve into the details. "I hate to interrupt your narrative," is a polite way of stopping someone in the middle of a story. The origin of this noun is the Latin adjective narrativus, from narrare "to tell," from gnarus "knowing." It is related to our English verb know.