Idea for Story

It begins with the main character walking down a narrow dim lit corridor. They can hear echoing voices. When they open the door at the end of the room they realise they have walked in on a crime. They hear the door slam shut behind them and they get knocked out with a blow to the head. The fall to the ground and the shot blinks in and out of focus in the perspective of the knocked out person. There is the sound of a gun shot and a person falls to the ground dead. When their body hits the ground everything goes black. Suddenly a bright light appears and slowly the person who walked in on the crime comes into focus. They are being interrogated by an investigator on what happened. With each question they flashback to what they remember, but parts of it is missing. The story is about the person lowly regaining their memory and realising who killed the person and why they were killed