Here's why:
* Mystery: The story revolves around a group of people with secrets, and a murder that needs to be solved. The reader is kept guessing about the culprit's identity throughout the book.
* Thriller: The story is filled with suspense, danger, and intrigue. The characters face threats and danger, creating a sense of urgency and tension.
It's worth noting that the book also touches on elements of psychological thriller as it delves into the characters' motivations and the impact of their past on their present actions.