The Last Novel : HUMANS, <i> By Donald E. Westlake (The Mysterious Press: $18.95; 355 pp.)</i>

Suppose God isn’t dead, merely tired . . . of the human race.

Suppose, too, He is so fed up that He sends an angel to obliterate this wearisome ball of rock, water and flesh.

Finally, suppose that the angel chooses an underachieving burglar, a former Brazilian rock star, a wholesome female bank clerk, a victim of the Chernobyl nuclear accident, a Kenyan prostitute with AIDS and a suicidal Chinese dissident as his agents of destruction.

From these sublime and base materials, veteran caper novelist Donald E. Westlake has created a cosmic thriller. Billed on the cover as “the last novel you will ever read,” Westlake’s latest blends theology, current events and witty twists of tried-and-true narrative techniques. Not least, the chief character is an angel, a convenient deus ex machina always on call for plot support. Thus, “Humans” is loaded with enough improbability and impossibility to please Supreme Beings of every faith.

In a way, that may be a major purpose of the book, to satirize the cleverness and conventions of the typical thriller through the stereotypes and literary mechanisms of an earlier, more faithful era. If so, Westlake has succeeded in his stated purpose: namely, to write a novel that departs from anything he has done before.

Anyway, enough analysis.

Once God sets the ball rolling in “Humans,” Heaven won’t wait. Earth must be eliminated right now; God has been annoyed long enough with the whining, petulant, over-breeding human race. Summoned from celestial limbo, the angel Ananayel wastes no time--eternally speaking--devising a suitable scheme for converting the world to an inert lump.

Fortunately, the angel has a good, though cruel, imagination. No lust or vice is too reprehensible to be turned to Ananayel’s use. Ananayel also is blessed with a wealth of subterfuges. The angel can be in two, or more, places at once. The sexless being is a master of corporeal disguise, capable of appearing either as a man or a woman. It can even seem to be two different people to various observers in the same place. Very handy, indeed. On a nuts-and-bolts level, Ananayel is pretty good at stealing cars, forging documents and rigging magazine contests. (Win a free trip to Moscow!)

Mostly, though, Westlake’s angel is an extremely efficient travel agent, providing airline tickets, money and moral support for the hapless characters. Half the fun of the book lies in discovering how the people in “Humans” reach the appointed time and place for Doomsday. By themselves, these puppets of God’s will aren’t capable of much more than injury-free visits to the bathroom. Clearly, nothing short of divine intervention could accomplish all of the following: smuggling the Chinese dissident out of Hong Kong, springing the penniless prostitute from Nairobi, spiriting the burglar from East St. Louis to New York and engineering the release of the Chernobyl victim from a Moscow cancer ward.

Adding to the suspense, the angel must make his pawns believe they are acting on their own. At one point Ananayel muses: “God has always nudged men, has engaged in confidence tricks and little scams, has played at times with a stacked deck, has thrown up illusions and toyed with mirrors, all to get humankind to want to do what God has in mind.” (Free will, it seems, got lip service in high places even before the death of deterministic communism.)

Naturally, the characters get to Armageddon on time. Appropriately, the site is a nuclear-power plant in Upstate New York where a scientist is trying to isolate “strange matter.” Whatever the stuff is, “strange matter” annihilates ordinary matter. If only a speck escapes the lab, it’s lights out for life as we know it.

In this final section, “Humans” becomes more and more like the standard thriller it parodies. In particular, a cliff-hanging moment at the scientist’s lab reeks of thrillers past. The climax also is something of a whimper, considering the buildup. But by then, Westlake’s juggling of the sacred and the mundane has become a complex act. He should get passing marks for escaping his plot. He should get even better grades for the bold break he makes with his past in “Humans.”

True, the novel does not entirely succeed on every level and leaves some nagging questions. (What happens to the souls of the dead? Do they have souls?) Still, Westlake has written a different and enjoyable work, less serious than “Paradise Lost” and with a more entertaining story line than “Pilgrim’s Progress.” And there’s the added benefit of Westlake’s street smarts and his familiarity with places a lot lower than heaven.