The Thing on the Doorstep

It is true that I have sent six bullets through the head of my best friend, and yet I hope to show by this statement that I am not his murderer. At first I shall be called a madman - madder than the man I shot in his cell at the Arkham Sanitarium. Later some of my readers will weigh each statement, correlate it with the known facts, and ask themselves how I could have believed otherwise than I did after facing the evidence of that horror - that thing on the doorstep...