Certain so-called novels are to fiction what fast-food places are to restaurants, and "Vatican," by Malachi Martin, is a Big Mac of the genre.

It will not do, to continue the analogy, to make demands of this sort of novel that would be appropriate to those further along the continuum of fiction. Of course, if you have no taste at all for junk food, you will just drive on by. But those with at least a limited tolerance for franchise food will derive some pleasure from "Vatican."

The chronological scope of the book is vast, from 1945 to the near future, and its canvas wide. Mussolini's execution, the departure of the Nazis from Italy, the test at Alamogordo, the whole shifting political and economic scene in every continent, machinations in the corridors of the Vatican and, of course, papal elections -- these and dozens of other things are crammed between the covers of this massive "novelization" of half a century and the great globe itself.

The neologism seems appropriate, and not only because there is no hero of the novel; there are no true characters at all. Nor is being able to put things vividly before the reader's eye among Martin's gifts, though from time to time, a scene takes on sufficient reality to provide a comment on the others. Characters are introduced with instructions to the reader as to their importance, and Martin prefers to report on action rather than to display it.

The focus of the narrative is the Vatican -- the pope, the curial officials, the various levels of Roman bureaucracy and, more ominously, the Vatican Bank. Offices, functions and groups -- rather than people -- are important in this story. If there is a theme it is the contrast between secular and sacred history and the struggle within the church between its spiritual and more mundane functions and functionaries.

One thinks of Upton Sinclair, one thinks of "The Winds of War." Martin's central character is Richard Lansing, with whose arrival in Rome in 1945 the book begins and with whom it ends as well. Lansing is an American priest from Chicago who is -- though we must take Martin's word for this -- intelligent, shrewd, compassionate, admired and so forth. It doesn't really matter.

One way to read the book is as a roman a clef. Somewhat puzzlingly, Martin changes Pius XII into Papa Profumi, perhaps to ensure the reader one correct guess. There will be those who find Bishop Marcinkus in the book, and the late Cardinal Cody. There is the odd insistence on the fact that Lansing was born in Peculiar, Ky., though he is a priest of the Archdiocese of Chicago, where his father is a prominent layman and confidant of the cardinal archbishop who has chosen Lansing for a successor. Bernadin? I really doubt the book delivers up such identifications, but it seems to invite the thought that it does -- or would to the knowledgeable.

The author was a priest in Rome before being reduced to the lay estate. Like many former clerics he has continued to earn his bread by relying on his churchy past. For a time he was religion editor of The National Review. His nonfiction books are, I think, far better than "Vatican." In "Hostage to the Devil" he brought together what were alleged to be tape recordings of exorcisms. The symmetry of that book made one wonder how much Martin was doing to the transcripts. In the case of "Vatican," I wish he had done a lot more in the way of turning the narrative into fiction.

For all that, I suspect that a lot of people are going to drive up to the window and order a copy. Over a million sold, that sort of thing. Not much nourishment, not, in the phrase, much beef, but not wholly without merit. For many it may create the illusion of being behind the scenes and in the know at last.