Synopsis of story:

Mary, an English woman, receives an anonymous package every year on the day her father disappears. The disappearance of her father ten years ago was an unforgettable experience for her. This year, she received a letter from the ghost sender, asking her to meet late at night. With the help of Holmes and Watson, Mary met the mystery man. However, the meeting did not reveal the truth, but brought them more questions. The mystery man died suddenly after leaving a clue. This clue made Holmes and his family determined to find out the dangerous and unpredictable truth behind this unique crime.

In addition, personally, I think the later novels The Hound of the Baskerville and uncanny valley are also good.