What are the scary details in the movie Invisible Guest?

At the end of the movie, when the key appears on the bed. The man's first reaction is to look in the mirror, because he obviously knows the entrance to the secret room.

It's strange that when Anna found the key in the movie, the man didn't question it. Because he has watched countless videos left by the female host, in which the female host always carries the key. It's impossible that he didn't know the key, but he didn't ask, so Anna always took it with him. There are two possibilities:

1. The man knew the existence of the key and the secret room through the landlord, but he didn't know where the key was until Anna found it, but he didn't mean to save the woman.

After knowing the existence of the secret room and the key, the man hid the key. Anyway, he knows the key, but he doesn't want to save that woman.

Introduction of main roles:

1, Belem echeverria

The designer of women's shoes came to Colombia with her boyfriend Adrian, and the shoe factory she designed was in Spain. They are fond of Emma's dog Hans, and when they are angry at the ambiguous information of Adrian and his colleagues, Emma tells the story and key of the secret room.

2. Adrian Salamanca

Young symphony orchestra conductor, very talented and talented. My girlfriend Belem and I came to Colombia from Spain and rented this mansion. After Belem left only one video, he was soon with fabiana claudino, the waitress in the bar.