The hidden horror

Is a horror story by H.P. Lovecraft, narrated in the first person, which recounts a narrator's investigation of an abandoned mountain mansion known for unexplained events and violent deaths. The investigation leads the narrators to discover a colony of subterranean cannibalistic creatures, genetically related to the Martens family, who inhabited the mansion. The narrative describes terrifying encounters with these creatures, including the loss of his companions. The story culminates with the destruction of the mansion and part of the mountain to eradicate the threat, leaving the narrator traumatized but eerily certain of the existence of other similar horrors.