BOOK REVIEW / NOVEL : Indecisive Moment Makes for a Terrifying Ordeal : KISS OF THE WOLF <i> by Jim Shepard</i> ; Harcourt Brace, $19.95, 263 pages

In shock when her husband walks out with no more explanation than a scrawled note tucked under the telephone, Joanie Mucherino lives in the bell jar of depression: nothing but white noise and white silence.

Her high school students pity her; on the other hand, a friend once told her that people are responsible for the bad things that happen to them. Twelve years of marriage have reduced her world to her job, her 11-year-old son, her relatives and a neighbor or two. She goes through her address book:

“It’s not a pretty sight. Whole letters of the alphabet are empty. Not just Q’s and X’s either. Where’re the F’s? Where’re the J’s? I don’t know anyone whose name begins with J? Some letters have, like, on a whole page, one uncle listed.”

With her sense of herself so shaken, her sense of self-preservation is also shaken. She half-welcomes the flamboyant attentions of Bruno, a self-proclaimed tough guy who has been after her for years. Her driving has turned fast and sloppy. One night, speeding home from a family confirmation party for Todd, her son, she hits a man walking on the road and kills him. She dithers; then, despite Todd’s pleas for her to call the police, she drives home and says nothing. It is not really a decision; it is a depressive inability to make a decision:

“What frightened her most was her inability to picture the terrible things ahead.”

At this point in Jim Shepard’s new novel, we are prepared for twists of character and event--remorse, discovery, an expiation ranging from inner torment to actual punishment, and possibly some form of growth--that fit within the quiet serio-comic realism of his characters’ voices and of their Italian-American working-class setting.

What we get is something quite different. “Kiss of the Wolf’s” low-keyed, finely tuned machinery begins to rev up ominously through mounting suspense and into a crashing, melodramatic finale.

The accelerator is Bruno. We see him--as we do Joanie, Todd and Joanie’s mother, Nina--sometimes in his own first-person account and sometimes through the eyes of another character.

He makes his first appearance at the confirmation party, a thoroughly dispirited affair where everyone is trying to overcome their dismay at the breakup of Joanie’s marriage.

Bruno, by contrast, is all exuberance. He is awkward, jovial, loud. The party needs his energy, but there is something wrong with it. He takes up all the room and his own clangor isolates him. “Bacigalupe”--wolf’s kiss--is Nina’s contemptuous nickname for him.

The nickname darkens. The dead man, somewhat too coincidentally, turns out to be a friend of Bruno’s. Not only a friend, in fact, but an associate in a Mafia-backed venture. An envelope full of money is missing. Bruno vows he will find the hit-and-run driver; not just out of friendship but because otherwise he himself may very well end up dead. At the same time, he resumes his pursuit of Joanie, showing special warmth not only to her but to Todd.

For Joanie, frozen in guilt and numbly reproached by Todd for her concealment, Bruno’s attentions hold an alarming ambiguity. He is ponderously affectionate but there is a whiff of menace as well.

Does he suspect her or is it simply a part of the dangerousness he prides himself in? Is he wooing her or trapping her? It is not just a question for Joanie. Shepard, author of “Lights Off in the Reptile House,” is a skillful and powerful writer, and almost until the end Joanie’s question and her terrified uncertainty are largely the reader’s, as well.

Shepard evokes the claustrophobia and isolation of her silence and, more touchingly, the torment of her son whom she has imprisoned in it. In Bruno he portrays a man whose image of himself oscillates, sometimes engagingly and sometimes spookily, between self-knowledge and delusion.

“Kiss of the Wolf” is an uneven effort. There is some artificiality in the setting-up of Joanie’s terror, and Shepard’s buildup can be creaky. The terror itself, and its awful constriction, on the other hand, are utterly convincing.

Joanie’s dealings with her family--particularly with her mother--are wittily and perceptively written, though television sitcoms have cast a preemptive shadow over domestic comedy that Shepard does not entirely escape.

As for the finale, its actual violence is much inferior to the implied violence that had held us until then. Like fictional sex, fictional mayhem is usually more convincing when suggested than when spelled out.