THE LEAGUE OF NIGHT AND FOG By David Morrell Dutton. 400 pp. $17.95

DAVID MORRELL does assassins, as those who are familiar with his recent books well know. In The League of Night and Fog, he outdoes himself. If there are not quite enough assassins in this novel to fill RFK Stadium, there is certainly a sufficient number to stock a new spring football league. Not only are Morrell's bad guys assassins, but so are his good guys -- and, often as not, so are the assassins' spouses, siblings, parents and offspring. When strolling through Morrell's neighborhood, one is well advised to keep a very wary eye on even the local clergy. Perhaps especially the local clergy.

And there's not a loafer in the bunch; all of these professional assassins are kept very busy. Saul Grisman, he of The Brotherhood of the Rose, is back, married to the beautiful and -- need one add? -- deadly Erika. With his wife and son, Saul is in retirement and keeping a decidely low profile in a remote Israeli village in order to avoid the wrath, and bullets, of the world intelligence community, which he so grievously offended in the past when he bumped off his spymaster foster father. But when Erika's father mysteriously disappears and they are subsequently almost killed in an ambush, husband and wife gird their loins for battle and trek out of the desert in order to take care of business.

Meanwhile. Somewhere in Egypt. Drew MacLane is keeping an even lower profile, with a very strange companion in a very strange place, repenting for his sins, practicing freshman mysticism and, not incidentally, seeking to escape the wrath, and bullets, of the people he so grievously offended in The Fraternity of the Stone. His lost love, Arlene, arrives just in the nick of time to save him from his own stupidity and to announce that the Fraternity, which has known all along where he is, will forgive and forget if Drew will look into the matter of a certain Prince of the Church who is missing. Drew and Arlene gird their loins for battle, escape an ambush, and trek out of the desert to take care of business.

Meanwhile. Somewhere in Canada. Uneasy sits a mysterious group of middle-aged men whose fathers have been disappearing at an alarming rate and whose destiny may be linked to yet another of the horrors perpetrated by Hitler and the SS in World War II. Two members of this group are sent off to take care of business. Care to guess the profession of these two men?

Now, having set loose three teams of assassins, with assassins to chase assassins, to search for, respectively, old men and a cardinal, Morrell is just getting warmed up. Alas, the plot will boil over more than once before he is finished, with the novel coming perilously close at times to resembling a parody of the genre. There are lapses, distracting and superhuman feats of observation which an editor should have persuaded the author to omit; for instance, it may be difficult for some readers to understand how a dozen assassins can literally rub dirt all over their hands (to avoid detection) without getting any under their fingernails or otherwise spoiling their manicures.

BUT ENOUGH of this petty carping; nobody likes a cranky critic with nothing good to say and there is much about this book that is splendid, state-of-the-art in the action/adventure (but not spy) genre. To complain that Morrell's prose is merely workmanlike is akin to being disappointed at not finding any orchids in a mountain meadow. Morrell is a wildflower of a writer, durable and tenacious, producing flat, foot-in-the-face sentences which do their job, which is to keep the reader turning the pages. No flowery metaphors for him; he is, first and foremost, a storyteller and a good one. If the book at times seems overplotted, bear in mind that you're getting two sequels for the price of one; if the rapid cuts sometimes make you think you're reading the literary equivalent of a music video, you'll still keep right on tapping your foot to his tune; if the characters never stand still on the page long enough for you to really get to know or like them, you'll nonetheless watch, wide-eyed, as they go through their paces.

Morrell's forte is action, and there is plenty of that here (one scene in particular -- with one of our assassin-heroes dressed only in his shirtsleeves and slowly freezing to death as he battles for his life against three men in the midst of a blizzard high in the Swiss Alps -- will have readers shuddering on their beach blankets, no matter how hot the sun). The author does manage, for the most part, to keep this speeding vehicle on the road, careening on two wheels around innumerable bends and twists in the plot. The patient reader will be rewarded with at least one very neat surprise about three-quarters of the way through the book, when some of the characters and groups begin to show their true colors, and from that point on all the threads begin to weave together and the story races on to its satisfying, if predictable, conclusion -- a kind of macabre family reunion toasted with gunfire, horror and hatred and marred only by some moralizing which sounds gratuitous, if not downright incredible, simply because it is mouthed by people who have made careers out of killing people, for reasons far less compelling than those harbored by the people they are moralizing to.

There is one thick, loose thread the author has purposely let hang, and from it he will undoubtedly weave another novel like this one. David Morrell kills off a legion of assassins in The League of Night and Fog, but there are obviously a lot more where they came from

. :: George C. Chesbro's most recent novels are "Two Songs This Archangel Sings" and "Veil."