How does the formation of the plus que parfait work? You will see the adverb déjà (already) quite often with this tense. For example: “When I walked into the room, you had already prepared dinner.” This second part of the sentence, “you had already prepared dinner,” indicates that this action had been done before “I walked into the room,” and this would be translated with the plus‐que‐ parfait tense: tu avais déjà préparé le dîner. In a nutshell, the Plus‐que‐parfait is used to describe an event that took place before another event in the past. In addition, it is directly translatable as the past perfect in English (the equivalent of “had + the verb”). It has a clear and logical explanation it isn’t ambiguous like the passé composé and the imparfait.
What is so perfect about the plus que parfait? Well in my opinion, this tense deserves to have the word parfait in its name because unlike the other 2 past tenses, it is easy to understand how and when to use it.