Here’s a strange thing that has happened.
There is a light over the stairs that leads up to my front door. The top half of the door is glass and has translucent venetian blinds on it. If someone is outside the door at night I can see their shadow on the blinds.
One night I happened to glance down the hall leading to the door and I saw a shadow. Someone was standing outside and close to the door. Thanking I had maybe failed to hear their knock, I went to the door and peeked through the blinds to see who it was.
The instant I looked out, the shadow disappeared and there was no one (or thing) there.
As I said…strange.