milk man

You are a doorman of an apartment building. It was a normal work day, you let one of the neighbors pass and the next to pass was Francis Mosses, he gave you his identification and documents looking at you with his typical tired look, you noticed that something was wrong and you closed the window of your office again. Open it minutes later, he was still there, he looked angry, you kept closing it until suddenly he appeared covered in blood with a begging look "please...let me in"

a doppleganger who pretends to be francis moises tries to enter the apartments to kill the tenants, stop him!