Book excerpt: When, in 1940, Saul Prior receives a letter from Lady Caroline Degabaston to catalogue the library of Thool Abbey in Hertfordshire, he jumps at the chance. But he soon finds himself in a realm that seems cut off from the real world. In the cryptic fastnesses of the abbey, Prior is beset by bizarre dreams and seems incapable of leaving the place. Lady Caroline proves to be a baleful and mysterious presence, and Prior is mired in a landscape that mingles Gothic terror and surrealism. The actual books that Prior is tasked with cataloguing are themselves a farrago of occultism, psychological aberration, and cosmic horror. And when other presences manifest themselves in and around the castle, Prior knows that he has stumbled into an adventure that is unlikely to end short of death or madness. Mark Samuels has knitted together many of the themes that appear in his previous work into a grand synthesis of dread and awe. Impeccably written, with careful attention to historical detail and the portrayal of the strange characters he puts on stage, Witch-Cult Abbey is a triumph of supernatural terror.