The Whisperer in Darkness

When strange things are reported to be floating in rivers in rural Vermont after a flood, old myths about hill-dwelling monsters who abduct humans resurface in subsequent debates, much to the annoyance of local academic Albert N. Wilmarth. However, when he starts receiving letters from a man named Henry Wentworth Akeley about the supposed presence near his farmhouse of an extraterrestrial race worshipping ancient cosmic deities, Wilmarth finds himself drawn into an astonishing correspondence that leads to a harrowing discovery.