The Young Marshal's Secret Lover

After the heroine's sister is killed in a trap during a mission, she receives a token and suspects foul play. Upon arriving at the station, she gets a note from the young marshal to meet at their usual spot. Going to her sister's former workplace, she is mistaken for the deceased sister, prompting her to assume her identity to uncover the killer and seek revenge. Later teaming up with the young marshal, they begin to unravel the shocking truth behind her sister's tragic death.