First, something I would have mentioned, except that that I didn't want to set you too much homework, was a certain resemblance of the "A.D. Harvey" case to that of "T.J. Wise". The Wise affair is a touchstone in the (admittedly small and specialised) world of historical bibliography; that is, the study of the history of the physical means of production of books and other printed matter.
The year of my life that I endured studying for a master's degree in library and information studies at University College London was greatly enlivened by a course on historical bibliography given by Nicolas Barker, then at the British Library. It struck me after a couple of his lectures that here was a man who should immediately be given a TV series; Nicolas Barker is the David Attenborough of bibliography. Flamboyant, entertaining, vastly knowledgeable, and keen to inform, from the moment he removed his cycle clips and dumped a bicycle-basket filled with tatty leather-bound tomes onto a table, dramatically ripping one of them apart, I was spellbound.
Bear in mind that bibliography is potentially dull, dull stuff. It's all about how printers work, how books are constructed from printed sheets, how type founts (note that spelling, pronounced "font") are developed and used, how paper is made, and ultimately how that knowledge can be used to reverse-engineer a historical book, and thus decide whether it is an earlier or subsequent printing than another, almost identical printing of the same text. The holy grail, of course, being to establish the precedence of various printed editions of, say, Shakespeare's plays (quartos, folio, etc.). Nicolas Barker had the gift of making all this dry stuff seem compelling.
One of the most fascinating bibliographic tales is the way the relatively new systematic study of book production uncovered a particularly cunning fraud, whereby T.J. Wise, a respected bibliographer (in the literary sense), seeded his catalogues with "rarities", some of which (mainly those by 19th century authors) did not actually exist, but which he then proceeded to have manufactured and to sell at a good price to collectors. These items were freshly printed, but others were incomplete copies "made up" using leaves removed by Wise -- a trusted authority -- from items in the British Museum's collection. The book published in 1934 exposing the skulduggery, An Enquiry into the Nature of Certain Nineteenth Century Pamphlets, by John Carter and Graham Pollard, is a classic of investigative procedure.
The second thing, on "mad but somehow compelling quests" in general, was this cartoon by Max Beerbohm which I thought was highly relevant:
The Sole Remark Likely to Have Been Made by Benjamin Jowett about the Mural Paintings at the Oxford Union: "And what were they going to do with the Grail when they found it, Mr. Rossetti?"Illustration by Max Beerbohm from "Rossetti and his Circle" (1922)