The House On The Borderland By William Hope Hodgson (HardCover)
Hodgson wrote a trilogy consisting of Date 1965 Modern
Warfare, The House on the Borderland, and The Ghost Pirates.
The setting for The House on the Borderland is an ancient
house in a lonely part of Ireland, where an old man lives alone
with his sister and his pets. His diary is found and it tells the
story of a huge cavern below the house filled with white pig
like monsters. The old man has had to fight these creatures.
He then sees his house in an alternate space-time plain that is
isolated from the rest of his world. This haunting tale conveys
intense isolations and loneliness.