Synopsis：Zena is a genius detective who can solve any case with logic and self-defense skills. One day, her girlfriend, Lucy, was found dead mysteriously, without any illness or injury. In the hands of Lucy's body, there was a clue to her death, in the form of a short letter containing the name of the company where she worked. To investigate Lucy's death, Detective Zena disguised herself as a plain and nerdy man, then applied for a job as a janitor at the company where her girlfriend used to work. There, Zena found that everyone had a motive to kill Lucy. But, who was the real culprit?