Salvage and demolition

"Richard Blanzac, a San Francisco-based rare book dealer, opens a box of consignment items and encounters the unexpected. There, among an assortment of literary rarities, he discovers a manuscript in verse, an Ace Double Novel, and a scattering of very old cigarette butts. These commonplace objects serve as catalysts for an extraordinary-- and unpredictable-- adventure. Without warning, Blanzac finds himself traversing a 'circle of discontinuity' that leads from the present day to the San Francisco of 1957. Caught up in that circle are an ancient Sumerian deity, a forgotten Beat-era poet named Sophie Greenwald, and an apocalyptic cult in search of the key to absolute non-existence" -- from publisher's web site.