I have to say, I was immediately intrigued with the title, it has a brilliantly simplistic flare to it. Especially with the simple descriptor, like something you'd see on a classy movie poster.

It is interesting that you never divulge really what the 'knock' is or even if it is real. However the sense of tension is a bit lacking in this tale.

I'd recommend building the psychosis of the narrator up a bit, give him a reason to be hallucinating this strange knocking, some suspicion that it might be something malevolent.

I was reading this in the dark and I actually walked over and opened my closet door. You know...in case. ;)
Anyway, great story! Utterly disturbing. Really gets the reader thinking about all the possibilities...
Keep writing!

~Cerulean K. Harmony~

Bone chillingly good. It really gets the mind to wonder about where the speaker really is and all the worst possibly scenarios of what's causing the "knock".

Well done.

Oh. Scary. . .

You wrote this really well. Good work!

Keep it up!

- Koki

Whoa...creepy. I imagined I was in there with the knocks and you almost made me scared >_<

Extremely good job by the way.