Wei Ying Luo voluntarily entered the Forbidden City during one of the Imperial Family's servant recruitment batches. She had a hidden agenda which was to find the person who had murdered her blood sister. She began her time there in the Sewing Department as an embroiderer.
She came to Empress Fuca Rong Yin's attention for her quick wits and bold personality. She soon and quickly rose to become one of the Empress's closest and most loyal maidservant.
After Empress Fuca Rongyin's death, she voluntarily served in one of Emperor Qianlong's summer palaces (Yuanming Garden) as caretaker but had to devise a way to re-enter the Forbidden City after discovering that there were suspicious incidents surrounding the Empress's death and she needed to return to investigate.
(Source: MusicalVeggies at MyDramaList)