BOOK REVIEW : When Fate Loses Out to Wishful Thinking : TRICK OR TREAT, <i> by Lesley Glaister,</i> Atheneum, $17.95, 192 pages

Nell, the fastidious widow in Lesley Glaister’s absorbing new novel “Trick or Treat,” is the sort of person who produces shivers.

When her only child, a sexually disturbed ex-con named Rodney, asks if he can move back into his old bedroom, Nell’s reaction is cold and deliberate.

“How much more satisfactory the hope of Rodney’s return had been than the fact of it,” she thinks. “How much more satisfactory to see the smooth clean bed, the innocent toys and books waiting. And how terrible to have a middle-aged stranger besmirch her memories.”

Memories are the food upon which Nell lives--she talks to a portrait of her late husband, Jim, as if he were alive and unchanged--as indeed do most of the characters in this accomplished novel (which takes place in a town resembling Sheffield, England, where Glaister lives).

At its center is the long-standing feud between Nell and her neighbor, Olive; the childhood friends became rivals more than half a century ago--back in their school days, when the two were regarded as “clever girls, the top of their class.”

The feud is rather one-sided, however, for although Olive, now 80, has become grossly obese, she can boast a relatively happy home life with her companion, Arthur, two beloved pets, and--most frustrating of all to Nell--memories of conquest.

It was Olive, not Nell, who narrowly won the school prize, and Olive who charmed all with her breeziness and beauty . . . including Nell’s own father.

Although Nell and Olive remain neighbors, they never speak; their ancient falling-out has become a solid, even reassuring aspect of their lives. But that changes with the arrival of new neighbors--Rodney, of course, but also the family now living in the house that stands between those of Nell and Olive.

The new family, which consists of Petra, her youngest son Wolfe, and his two siblings, invite Nell, Rodney, Olive and Arthur to a back-yard celebration of Guy Fawkes Day, complete with fireworks and a burning scarecrow.

Quite unaware of the enmity between Olive and Nell, they are not prepared for the scene that subsequently unfolds.

Nell goes on about Rodney and “my Jim,” intent on taunting Olive with the fact that she never married and has no living children. Nell blithely mentions the scarecrow’s now-burned hat, which she believes was Olive’s favorite; Nell had given it to Wolfe with just such destruction in mind after chancing upon it.

Olive, always quick to anger, hints darkly that “there’s things I know about your Jim that would wipe that look off your face,” leading Arthur to take her home with many apologies.

The damage has been done, however, for even as Nell goes on about Olive’s “delusions,” we know that she is the one who constantly rewrites the past.

Rodney, ultimately, will do much more than besmirch his mother’s carefully guarded memories. Nell noticed the surreptitious advances Rodney had made toward Wolfe during the fireworks party, and when she finds him reading pornography in his room the next day, she becomes furious.

Nell throws Rodney’s old toys out the window after he leaves for a job interview, declares him “an impostor” and herself childless, just like Olive.

On an impulse Nell determines to make peace with her old friend--by giving back the school cup she had taken from Olive’s yard during World War II, after the house had been bombed.

Nell’s plans go awry, however, resulting in two deaths, but not before she is forced to confront her artfully buried past.

“Trick or Treat” is Glaister’s second novel--her first, “Honour Thy Father,” won the Somerset Maugham Award last year--and shows a writer very much in tune with the travails and resentments that dominate many lives.

Nell’s dismissive description of Olive is almost an understatement--”a fat old spinster, childless, senile”--but Olive becomes a sympathetic character despite her vanity, her bossiness, the weight that all but paralyzes her.

Arthur, the “boarder” who is in fact Olive’s lover, is a saint for putting up with her, yet he’s no stereotyped milquetoast; he’s an uncomplicated, uncompetitive man of principle, who served his country during World War II not by fighting but by growing food in a camp for conscientious objectors.

Petra’s family is less compelling--it exists mainly to bring Nell and Olive together--but Wolfe is a perfectly drawn child, equal parts trusting and fearful, uncertain and expectant.

It’s Nell, though, who makes “Trick or Treat” work. She’s not evil, precisely, but near enough, proud to be described, chillingly, as someone who “never let Hitler interfere with her routine.”

Nell sees herself as a victim, put upon by external forces, but it’s clear that her troubles--with Olive, Rodney, in the past with Jim--are largely of her own making. Nell’s comeuppance, as a result, is very satisfying, despite the fact that it’s neither expected nor fitting; Wolfe and Arthur, the two great innocents of “Trick or Treat,” seem destined throughout the novel to be Nell’s final victims.

No matter: Sometimes it’s a relief to encounter a literary work in which fate loses out to wishful thinking, in which only the wicked suffer.