The Fire of Love.

BOOK 9. Zhao Yunlan is a private investigator who will accept almost any case as long as it pays, and when he finds a client's lost cat, they ask him to look into their friend's memory loss but he refuses. Shen Wei is an architect and after he meets Yunlan by accident, they have a wonderful evening out at an art gallery owned by the person who lost the cat. Things are not what they seem. No one knows that Wei is being threatened with the lives of his friends while an unseen guest watches his every move, constantly.