You hear a polite knock on the door . The closet door .

So there I was, sitting at my desk, when I heard a polite knocking. 
 
 I head to the front door, nobody is there so I assumed I was just hearing things. Then I sit back down back at my desk and continue with my pointless browsing. 
 
 Then I hear the knock again. It sounds just like a salesman kind of knock, polite, soft but loud enough to be heard, well practised and rhythmic. 
 
 And so I try the front door again, but there is nobody there. 
 Then I try the back door too this time in case the guy was cheeky enough to go through the latched garden gate. Yet again nobody there. 
 
 Well, of course I'm annoyed a bit, but not enough to care much at this point. 
 
 Then right when I'm still standing at the back door. I hear the knocking again... and it's definitely not from the front door. 
 
 Well now I reckon that some machine must be making the noise, maybe I left something on. I run around the house and turn off all stuff that might be making the noise. 
 
 Then as I'm about to sit down. I hear the knocking again 
 
 
 
 *hmm, I know the next step, trying to pinpoint the location of the noise and then actual plot opening up, but thinking of how to continue it is a bit of a ballache, trying to write like a informal retelling to a friend of something weird that happened. Will come back to it later*
