Could you please help me polish below English? Thanks in advance!
I love it! What a great surprise ending.
In order to keep the original 'feel' I have made as few changes as I could to correct the grammar/English. Words to take out are in (RED), words to add are in (GREEN). Your teacher may wish to 'correct' other things, but I think it is fine like tihis. Good luck.
I had been feeling something quite fishy. One day I stopped the old doorman, and begged him to tell me the truth. He told me, " A sweet couple lived in the apartment ahead of you. One day they flared up into a ferocious fight somehow overnight. The woman evaporated since then, and no one ever saw her again. The guy vanished subsequently after remodeling the apartment. Neighbours noticed the man always whitewashed his walls around midnight. Word had it the guy might have murdered and buried his lover (into) in the wall." I felt grisly after hearing the plot.
After going back, I combed my residence here and there, up and down but little tinge of (the) a clue was detected. As I sat in my bed exhaustedly, my eyes were stuck to a dubious spot marred by water on the cross wall. The more I gazed (at,) the more it looked like a figure struggling to burst forth. I got my goose bumps, curled myself up in a blanket and slept.
I had a (night mare) nightmare at that midnight, seeing a couple (who) quarreled boisterously. The man strangled the woman with a rope on a rampage, and then built her into a wall. I saw fresh blood sheding out of the woman's eyes, and she was desperately struggling in the wall and kept screaming, " set me freeeeeeee! seeeet me freeeeeeeeee!!!...". I was so scared that it woke me up. I couldn't bear it any more and started digging into the wall with a screwdriver.
At last, appeared a small hole, then I caught an eye (was) sullenly staring at me inside ...
Good heavens! It came true...
The eye was turned by a mouth, blustering,
'Dude, Why the hell are you digging through our wall..."