Their Phantom

Their Phantom summary:

A shady undercover police officer x an innocent university student. In an accident, university student Song Xiao An is kidnapped and brought deep into the mountains, ripping her away from her peaceful and happy life. There, an undercover police officer named Zhou Si Han secretly takes care of her, and Xiao An thinks she can escape through her. However, she discovers that the policewoman is hiding a dark secret...