BOOK REVIEW / NOVEL : Of Pompous Washingtonians, Spies and Getting the Girl : NIGHT OF THE AVENGING BLOWFISH <i> by John Welter</i> , Algonquin Books $10.95, 304 pages

John Welter writes a humor column for a North Carolina newspaper, which is what’s best and worst about this endearingly weird novel. He’s very good at what he does, which is being funny, but his event is the sprint. Problems arise when he has to run a half-marathon.

Welter’s hero, Doyle Coldiron, is a disaffected member of the Secret Service, wasting his lonely life preparing for crises that may never take place. His job description demands that he be the perfect gent--which is to say, he never divulges anything about himself. But it’s beginning to grate. Doyle wants a woman. Specifically, he wants Natelle, who inconveniently happens to be married to someone else.

So Doyle fritters his time away planning a spook baseball game with the CIA and trolling for women with whom he isn’t supposed to discuss anything meaningful. One day he wanders into the White House kitchen, where Abbas the chef is plotting revenge on the President for a recent insulting comment about White House food. This night, he’s going to serve the President and his important guests cat-food canapes and Spam in lemon sauce--and Doyle ignores the little voice of conscience that tells him to turn Abbas in. Spam isn’t a weapon; the Secret Service doesn’t have to protect the President from pressed luncheon meat.

Which is how Doyle ends up in Secret Service hell, protecting the diminutive ambassador from Indizal. And how he ends up eventually being a hero. And how, because of his personal heroism and a bunch of other things he never even knew about, he ends up getting the girl. (I’m not giving away a surprise. It’s clear he’s going to get her early on; the funny stuff comes from the process of acquisition.)

The first chapters of this clever book are not unlike good humor columns: They’re disciplined, self-contained, philosophical and surprising; there’s lots of funny stuff. Welter is particularly fond of nonsense collisions--as in, the Secret Service prefers married men because the desire to return home to wife and children makes them sensible and careful in their work, but it prefers unmarried men because they have nothing to lose. Doyle is as full of well-articulated love and affection as a man can be, but it’s all aimed at the one women he can’t confess it to. The spooks want to play baseball, but they can’t divulge, even to each other, the location of their covert athletic operation.

There’s a lovely cadence to Welter’s writing; after awhile you can sense the rhythm. But with familiarity comes repetition, and that’s where Welter gets into trouble. We can’t read Natelle’s name, it seems, without being reminded of how much Doyle would like to spill the beans and how hard he’s trying not to. We can’t meet Doltmeer, his boss, without being reminded of--yep--what a dolt he is. Welter is a bit like the funniest guy in the crowd, who’s always expected to entertain at parties: He might have something more substantial to say, but the audience is waiting for more of what works.

And in this case he does have bigger ideas. He sneaks enough of them in to make the reader wish for more, for a bigger, broader story that takes even more chances. He has a nicely irreverent eye for Washington pomposity, and for the oddball collection of characters who exist at the fringe of that world.

His characters are sharp and idiosyncratic--and Doyle turns out to be much more than just another cynical, smart guy. Welter writes about Doyle’s feelings for Natelle with lyric delight, and about his own rising anxiety with refreshing frankness. A guy who yearns for emotional commitment and admits that life is meaningless without it? Talk about modern fiction.

So let’s hope that Welter writes another one that takes him just a bit further from his roots. He’s the kind of writer--and thinker--you want to hear more from.