It is August 1969. The Summer of Love is a fading memory. The streets of San Francisco pulse to the sounds of Led Zeppelin and Marvin Gaye. And young Ajax Penumbra arrives in San Francisco looking for a book—the single surviving copy of the Techne Tycheon, a mysterious volume that has brought and lost great fortune for anyone who has owned it.

The last record of the book locates it in the San Francisco of more than a century earlier, and on that scant evidence, Penumbra’s university has dispatched him west to acquire it for their library. At first the search is fruitless. But late one night, after another day of dispiriting dead ends, he stumbles across a 24-hour bookstore, and the possibilities before him expand exponentially…