He is not to open the door which leads to the strange time and place, nor to invite Him Who lurks at the threshold ..." went the warning in the old family manuscript that Ambrose Dewart discovered when he returned to his ancestral home in the deep woods of rural Massachusetts. Dewart's investigations into his family's sinister past eventually lead to the unspeakable revelations of The Great Old Ones who wait on the boundaries of space and time for someone to summon them to earth. Acclaimed cult horror writer H. P. Lovecraft's notes and outlines for this tale of uncanny terror were completed by August Derleth, his friend and future publisher. Of the many Lovecraft-Derleth "posthumous collaborations," The Lurker at the Threshold remains the most popular, having sold 50,000 copies in its previous edition alone.