William James Henry is the purported author of the thirteen notebooks discovered after his death in 2007, the first three of which make up The Monstrumologist. Born in the year 1876 to James and Mary Henry of New Jerusalem, Massachusetts, Will is orphaned at the age of eleven when his parents perish in a terrible fire. He is taken in by his father’s employer, Dr. Pellinore Warthrop, to serve as his assistant and, eventually, his apprentice in the natural science of monstrumology, of which Dr. Warthrop is the leading expert of his day. The first journal, or Folio, opens in the spring of 1888, when Will is twelve years old, and chronicles (with the Second and Third Folios) the strange case of the Anthropophagi Affair, the frightening and mysterious infestation of their little town by a race of huge, headless, bloodthirsty carnivores.

Young Will Henry will face many tests of courage, pluck, and fortitude that few men could pass, much less a twelve-year-old boy, confronting unthinkable evil and unimaginable horror. But, as he notes in his remarkable journal, “This is monstrumology, the science of the unthinkable.”

Widely recognized as the leading expert in his field, Pellinore Xavier Warthrop has devoted his life to the study of fantastical creatures normally found in nightmares. By turns mercurial and stoic, driven by ambition−the seed of which lies buried deep−he will sacrifice practically anything, including all human relationships and his own health, in furtherance of his goals. He is presented in Will Henry’s journals as a strange, paradoxical man, possessing a keen wit but a dull sense of humor; self-righteous yet just; egomaniacal yet empathetic; brilliant yet, at times, marvelously obtuse. We are granted glimpses only of Warthrop’s background and interior life. Educated abroad, raised by a strict, emotionally distant father (his mother died of tuberculosis when Warthrop was barely out of his teens), Warthrop seems to have found succor only in science and his “peculiar pursuits in natural philosophy,” i.e., monster-hunting. His presence looms over Will Henry’s writings, reflecting an intimacy rarely achieved even between a father and son. The memory haunts of Warthrop the man looking back at his childhood and the years spent under the monstrumologist’s shadow. Much of Will Henry’s story deals with his struggle to understand the man he calls “my mentor−and my tormentor.”

A strange and difficult man, Jack Kearns appears in Will Henry’s journals in answer to an urgent summons by Dr. Warthrop after Anthropophagi are discovered in New Jerusalem. His origin (perhaps Great Britain, perhaps not) as well as his true name (perhaps John Kearns, perhaps not−he offers many alternatives throughout the text, including “John Jacob Jingleheimer Schmidt”) are uncertain. He claims to have been a surgeon at one time, and certainly demonstrates some medical knowledge during the course of the horrific events described in the latter half of the journals (particularly Folio Three, Slaughter). As described by Will Henry, Kearns is tall, boyishly handsome, extremely witty and irreverent, well-traveled and well-read, and keenly interested in the subjects of morality and monster-hunting, though not necessarily in that order. There seems to be nothing he will not do to destroy the pod of man-eaters, no law that he won’t break, no ethical dilemmas he will consider. In many ways, he is the dark mirror image of Will Henry’s master, Pellinore Warthrop, his personality, ironically, closer to that of the beasts he hunts than the people he hunts with. As he confesses, “In many ways, I admire [the Anthropophagi].” By the end of the third journal, Will Henry makes a startling admission that this same Jack Kearns is a real person from history, a horrific murderer who is remembered as perhaps the most famous serial killer ever.