The old mansion in the woods north of Arkham had stood empty and shunned for more than a hundred years - until Ambrose Dewart arrived to claim his family inheritance.

But Dewart found a terrifying legacy awaiting him there: A window offering glimpses into some dimension of unearthly terror. A library of dark and secret lore. Names of creatures from the realm of madness: Cthulhu, Yog-Sothoth, Nyarlathotep. And local legends involving mysterious rites and the conjuration of Powers from beyond space and time.

And Dewart's arrival had brought the horrors to life again. Once more, the Lurker at the Threshold was preparing to come across...