The past perfect refers to a time earlier than before now. It is used to make it clear that one event happened before another in the past. It does not matter which event is mentioned first - the tense makes it clear which one happened first.
- She had lived in London. (It is a completed action in past and especially a long time ago)
- She had finished her project work last year.
- The movie had started before we reached cinema.
- She had not finished her project work last year.
- Had the movie started before you reached cinema.
- The train had already left when we reached the station.