The Return of the Sorcerer by the incomparable Clark Ashton Smith.
The story starts:
I had been out of work for several months, and my savings were perilously near the vanishing point. Therefore I was naturally elated when I received from John Carnby a favorable answer inviting me to present my qualifications in person. Carnby had advertised for a secretary, stipulating that all applicants must offer a preliminary statement of their capacities by letter; and I had written in response to the advertisement.
As you say the narrator has been hired as a translator:
Your knowledge of Arabic will be invaluable to me, for I am none too well-grounded in this language myself, and I am depending for certain essential data on a copy of the Necronomicon in the original Arabic text. I have reason to think that there are certain omissions and erroneous renderings in the Latin version of Olaus Wormius.”
The part with the hand in the hall is:
When I looked down and saw the thing on which I had almost trodden, my feeling was one of sick amazement and actual nausea. It was a human hand which had been severed at the wrist—a bony, bluish hand like that of a week-old corpse, with garden-mold on the fingers and under the long nails. The damnable thing had moved!
John Carnby had murdered and dismembered his brother (and fellow necromancer) Helman. The story ends:
A reddened knife and saw were protruding from the pile; and a little to one side, between the rug and the open cupboard with its shattered door, there reposed a human head that was fronting the other remnants in an upright posture. It was in the same condition of insipid decay as the body to which it had belonged; but I swear that I saw the fading of a malignant exultation from its features as I entered. Even with the marks of corruption upon them, the lineaments bore a manifest likeness to those of John Carnby, and plainly they could belong only to a twin brother.
The frightful inferences that smothered my brain with their black and clammy cloud are not to be written here. The horror which I beheld—and the greater horror which I surmised—would have put to shame Hell’s foulest enormities in their frozen pits. There was but one mitigation and one mercy: I was compelled to gaze only for a few instants on that intolerable scene. Then, all at once, I felt that something had withdrawn from the room; the malign spell was broken, the overpowering volition that had held me captive was gone. It had released me now, even as it had released the dismembered corpse of Helman Carnby. I was free to go; and I fled from the ghastly chamber and ran headlong through an unlit house and into the outer darkness of the night.
If you like this kind of gothic horror story then I wholeheartedly recommend you read more of Clark Ashton Smith's work. There are lots of collections of his stories available. As a young teenager I loved his stories and indeed preferred them to Lovecraft. As a sexagenarian teenager I have to concede that his prose is a little purple at times, but I still love his stories and regularly reread them.
