Poisoned Waters

The villages of Cawsand-Kingsand are suddenly stunned with the unequivocal evidence of an invasion of their villages some four hundred years ago, which had only been read about in books and disregarded as an imaginary tale brought forth at the time by a young man called Jason Tregoran.
It is not until Sergeant of police Roy Selley and his counterpart retired solicitor John Jago, make investigations into the evidence that they are physically drawn into another world six hundred feet underground, where an indescribable alien force dwell.
They eventually manage to escape with terrible repercussions. Although there is hideous carnage and horrific destruction to the villages, the surviving villagers have no knowledge of what has taken place.