H. P. Lovecraft 
The Whisperer in Darkness [EPUB ebook] 

‘The Whisperer in Darkness’ is a story by H. P. Lovecraft. The story is told by Albert N. Wilmarth, an instructor of literature at Miskatonic University in Arkham. When local newspapers report strange things seen floating in rivers during a historic Vermont flood, Wilmarth becomes embroiled in a controversy about the reality and significance of the sightings, though he sides with the skeptics, blaming old legends about monsters living in uninhabited hills who abduct people who venture too close to their territory.
He receives a letter from one Henry Wentworth Akeley, a man who lives in an isolated farmhouse near Townshend, Vermont. He affirms that he has proof that will convince Wilmarth that he must stop focusing on the race’s existence. The two exchange letters, including a record of the extraterrestrial race chanting with human agents, who worship several beings, including Cthulhu and Nyarlathotep, the latter of whom ‘shall put on the semblance of men, the waxen mask and the robe that hides’.
The agents intercept Akeley’s messages and harass his farmhouse nightly. Akeley and the agents exchange gunfire and many of Akeley’s guard dogs are killed. Although Akeley expresses more in his letters, he abruptly has a change of heart. He writes that he has met with the extraterrestrial beings and has learned that they are peaceful. Furthermore, they have taught him of marvels beyond all imagination. He urges Wilmarth to pay him a visit and to bring along the letters and photographic evidence that he had sent him. Wilmarth reluctantly consents.
Wilmarth arrives to find Akeley in a pitiful physical condition, immobilized in a chair in darkness. Akeley tells Wilmarth about the extraterrestrial race and the wonders they have revealed to him. He also says that the beings can surgically extract a human brain and place it into a canister wherein it can live indefinitely and withstand the rigors of outer space travel and shows proof to Wilmarth. Akeley says he has agreed to undertake such a journey and points to a cylinder bearing his name. During this conversation, Wilmarth feels a vague sense of unease, especially from Akeley’s odd manner of buzzing whispering.
During the night, a sleepless Wilmarth overhears a disturbing conversation with several voices, and a departing. When he investigates, he makes a horrifying discovery and escapes the farmhouse by stealing Akeley’s car. When the authorities investigate the next day, they find nothing but a bullet-riddled house. Akeley has disappeared, along with all the physical evidence of the extraterrestrial presence. Wilmarth reveals the discovery that drove him out was a disembodied face and hands. We are led to conclude that it was not Akeley who had sat in the chair and conversed with him but one of the Mi-Go in disguise, as Akeley’s brain was in the named cylinder.