The Thing on the Doorstep

'The Thing on the Doorstep' is a horror short story by American writer H. P. Lovecraft, part of the Cthulhu Mythos universe. It was written in August 1933 and first published in the January 1937 issue of Weird Tales.
Daniel Upton, the story's narrator, explains that he has killed his best friend, Edward Derby, and that he hopes his account will prove that he is not a murderer.
'He must be cremated—he who was not Edward Derby when I shot him. I shall go mad if he is not, for I may be the next. But my will is not weak and I shall not let it be undermined by the terrors I know are seething around it.' - Daniel Upton, 'The Thing on the Doorstep'.