Molly Gray is the 29-year-old protagonist. She has risen through the ranks to become the Head Maid at a boutique hotel called The Regency Grand, and she is very proud of achieving this position. She loves to clean and has always enjoyed this task. Her abhorrence of dirt also extends from the physical to the metaphorical in her dislike of immoral behavior. Molly’s beloved gran died four years ago and still has a strong influence on her thoughts and actions. This dynamic recurs throughout the novel in the form of flashbacks, stories, and aphorisms that Molly remembers whenever she needs guidance in difficult situations. The narrative also reveals that Molly was bullied by other children during her time in public school, and the school staff refused to address this problem or provide her with adequate support.

Molly is a unique thinker who notices subtle details but often misreads conversations and human behavior. She also speaks in a direct, honest way that sometimes offends those who are not familiar with how her mind works. This novel builds on the aspects of Molly’s personality that have already been established in the first book, The Maid, and in The Mystery Guest, Molly’s strict sense of morality becomes even more prominent.