Tolkien was big stuff in the late-1960s and his work was something Bellairs found worthy of sharing. Al Myers remembers one of the first Christmas gifts he received from Bellairs was the boxed, hardcover British edition of The Lord of the Rings plus a smaller hardcover edition of The Hobbit. "This was a full three years or so before the Tolkien craze in the States, but John was already well aware of him."

Bellairs' novel would be somewhat similar (i.e. heroic journeys across unfamiliar terrain while encountering an assortment of local oddities) but with his own twists: his wizard, Prospero, while archetypal in form, would be fashioned with "most of my phobias and crotchets," resulting in a wizard who not only knew long strings of spells, but could just as easily forget them (and at the worst-opportune times, too). Different too was his style of writing, moving between unsettling passages that describe eerie forests and visits by apparitions to laugh-out-loud moments involving sarcastic singing mirrors and goofy local sovereigns.

How far along in Prospero's tale Bellairs was before he arrived in Bristol is uncertain, but the ambiance there surely inspired him – note the similarities of local flavor found in the Gorgon's head in nearby Bath and Somerset's Five Dials Inn. When he returned to the states, Bellairs completed the story and readied it for publication.

Sadly, this was to be Bellairs' only published foray into the world of Prospero, a genre identified by author Wayne Gammond as the world of "Eccentric Fantasy, or the Nightmare with Comic Relief." Try as he might, Bellairs could not recapture the unique atmosphere and inspiration that he had for his original, something that Douglas Ander, whose mother was an aspiring author living near Haverhill and had met Bellairs, liked as a "common phenomenon" among creative people - "like Coleridge and 'Kubla Khan.'" But John did try: his son, Frank, recalled a notebook containing his father's hand-drawn maps and notes for a second book about Prospero and Roger Bacon that started and stopped at various points during the 1980s. One notable exception was the story, conceived as either a sequel or one involving new characters, that would eventually reemerge as The House with a Clock in its Walls.

Whatever motivation was lacking for a full-length book did not diminish Bellairs from allegedly composing a short-story detailing Prospero's origins. Perhaps one of the more cryptic and tantalizing passages about Bellairs and any unpublished works comes from Carter's Imaginary Worlds:

I wrote to him after reading The Face in the Frost, and we have been exchanging letters off and on for some time now. An affable chap, he has let me look at his sketchy maps of the South Kingdom and some unpublished scraps, notes, and outlines for these further adventures; and, in fact, he has produced for my yet-unpublished anthology of juvenile fantasy, entitled Magic Kingdoms, a new short-story which tells how his diabolic duo first became friends.