John Brunner 
Atlantic Abomination [EPUB ebook] 

AWAKEN, TERROR!When the first expedition descended to the bottom of the Atlantic in a perfected high-pressure diving bell, their speculation ran wild as to the wonders they would encounter in that unknown sea-bottom world.But their wildest dreams did not prepare them for uncovering first, the stones of an ancient civilization, and second, the monstrous body of an inhuman creature that had been sealed beneath the waters for countless eons.Then, at the height of their excitement, elation turned to horror. For they had brought back an abomination so old that the memory of it had been lost to man’s remotest ancestors. Shops were disappearing, men and women were becoming enslaved by invisible whips of mental mastery, and it began to look as if it might be beyond the powers even of modern science to stop something that had so successfully defied time and space.