LIMELIGHT. By Terence Feely. Morrow. 297 pp. $15.95.

LIVERPOOL is the setting for a rollicking romp in which we follow the adventures of Tara Stewart, child of the slums, as she moves from the mailroom of Alhambra Television to the role of star investigative reporter. Making full use of her blonde beauty, her native wit and the loyal friendships of young people who shared the crime-infested world in which she grew up, Tara becomes TV's avenging angel, infiltrating and exposing the seamy schemes used by the underworld to prey on the poor.

Tara also has a secret agenda: to avenge her wrongfully imprisoned father and bring to justice Shaun Pattison, the man who committed the daring s17,000,000 robbery for which Tara's father is serving a long sentence. To trap Pattison, who has used the spoils to build reputation of respectability, Tara employs concealed tape recorders and cameras along with such less savory resources as selective theft and blackmail in order to burrow through his network of accomplices.

Numerous complications ensue, the worst of which for Tara is that she falls in love with Pattison's son Michael, who does not know the truth about his father. Now she must choose between betraying her lover or her father.

There's not a dull moment in Limelight. As the story races to its slambang finish, we meet a host of memorable characters, among them Tara's mammoth Aunt Rita, a Scripture-misquoting, eternally suspicious alcoholic. In a passage illustrative of the novel's beguiling style, we see Aunt Rita arriving at the hospital where Tara is recovering from a motorcycle accident.

"She crashed through the swing doors at the end of the ward and measured her length on the polished floor, the swinging dangle of bags and carriers, without which she was constitutionally incapable of going anywhere, scattering their contents all over. They included a police truncheon, a Bible, half a loaf green with mold, an alarm clock and a large bottle of cider . . . She did not seem to have come to any harm. Tara had seen Aunt Rita tumble, like a gigantic sackful of foam rubber, down a flight of stairs and get up and carry on to wherever she was going without comment."

Limelight is chockful of such goodies. It makes for toothsome reading. THE FORTUNES OF WAR. By David Fraser. Norton. 476 pp. $15.95.

THIS panoramic story of World War II centers on seven young people who meet in Germany in 1938. Anthony and Marcia Marvell are a British brother and sister; Frido von Arzfeld, his brother Werner and his sister Lise are the children of a disabled German army colonel; Anna Langenbach, their cousin, is married to a Luftwaffe pilot fighting for Franco; Count Toni Rudberg is related to the Langenbachs.

Anthony falls in love wna and fathers the son born to her soon after her husband's death in Spain. Marcia, who elects to continue her nurse's training in Germany even after the war's outbreak, is betrothed to Werner but, after he meets death on the Polish front, is attracted to the devil-may-care Toni.

With this cast of characters the author guides us through the pivotal events of 1939-1945. Frido, a pawn in the Army officers' plot to assassinate Hitler, is executed when the plot fails. Anthony is captured in France, escapes from the prison camp and is briefly sheltered by Anna as he makes his way back to England. Anna is imprisoned for this act of treason. Toni, captured by the Russians in the siege of Stalingrad, spends 12 years in a Soviet prison. Marcia and Lise, working as nurses, evacuate their hospital in the face of advancing Red Army troops and barely make it across the Elbe.

Fraser spares us few details of the atrocities committed by all sides. Early in th war British prisoners in France are machine- gunned by a unit of Germany's Totenkopf Division; in reprisal, German prisoners are shot by a British unit. Or was the sequence the other way around? Each side accuses the other. On the eastern front, neither the Germans nor the Russians bother much about taking prisoners. Red Army soldiers moving westward into Germany rape and pillage; Marcia's hospital treats young peasant girls whose nipples have been bitten off.

David Fraser is an Englishman, but his masterfully written narrative is scrupulously free of bias. War turns people into animals capable of anything, he implies, and no nation has a monopoly on morality. Fraser understands and cares about all of his protagonists, and so do we. THE TRAP. By Tabitha King. Macmillan. 312 pp. $15.95.

LIV RUSSELL, potter, wife, mother of two, is discontented with her life, her marriage and the social set of the summer colony in northern Maine where the Russells have a cottage. Picking berries in a neighbor's woods, she encounters three local ruffians who have caught a cat in a trap. They jeer at her protests and, as she watches in horror, one of them crushes the cat's skull under his heel.

Liv and her five-year-old son Travis have made friends with the elderly spinster Helen Alden, whose family has lived in Nodd's Corners for generations; one day Miss Alden shows them her house's secrets -- a horde of shotguns and a concealed passage built alongside the chimney.

All of these elements come into play when Liv makes an angry decision to return to the cottage in midwinter with Travis. Sarah, her teenage daughter, is left behind with grandparents to finish out the school year; Pat, her screenwriter husband, is off to California to finish a movie script, a violent drama about Vietnam veterans, sections of which interleaf the novel's main storyline.

Terror begins when the three hoodlums, on a rampage of robbing and vandalizing the closed summer cottages,discover that Liv and her boy are alone; it ends only after bone-chilling mayhem and rape have been perpetrated, and a rough measure of justice has been achieved.

The author and her husband, Stephen King, have divided the world of literary goosebumps between them; his thrillers focus on the supernatural, hers on man's basest instincts. Both excel in their respective approaches. THE TWELFTH OF APRIL. By Roy Doliner. Crown. 306 pp. $16.95.

THIS meandering tale rests on a body of historical truth: that among the post-revolutionary exiles from Soviet Russia who moved to the West were some who spied for the Communists and others engaged in counterintelligence. But it then abandons fact to propose the extraordinary theory that Franklin D. Roosevelt's death on April 12, 1945, was caused by an assassin acting on Stalin's orders. Fact is equally ignored in the depiction of FDR's longstanding affair with the woman who was with him in Warm Springs when he died; the novel has Roosevelt secretly visiting her New York apartment during the 1920s -- years when, confined to a wheelchair, it was impossible for him to go anywhere unattended or unobserved.

Although the book's title suggests that the death of FDR is its main focus, the dominant thread is actually a kind of love story. Serge Dolin, hand-picked by Stalin to execute the series of killings culminating in Warm Springs, is aware that, once he has accomplished his mission, he, too, will be scheduled for extermination; in Stalin's style, none who know his secrets are allowed to survive. To evade such a fate, Dolin escapes to Mexico, leaving his wife Magda and their unborn child in Canada. When Magda later joins him, abandoning their son, they spend 25 years slinking from country to country. It is not only Stalin's henchmen they fear; also on Dolin's trail is the shadowy American millionaire Andrew Winters who heads "Living Memory," a network of anti-Communist spies and informants. The chase ends in a stalemate for all concerned.

The story, which begins in 1920 and ends in 1970, is narrated by the physician Irina Markova. A rather pointless second romance, that of Irina and "Living Memory" member Vladimir Bogdonov, occupies far too many pages of an overlong, overpopulated and ultimately boring piece of fiction. ARIANA. By Edward Stewart. Crown. 466 pp. $17.95.

IF you have even a superficial acquaintance with the lives, careers and foibles of modern opera luminaries, you will have little difficulty identifying the faintly disguised originals of the characters in Ariana. Finding the keys to such easily unlocked doors may be just about the only pleasure to be derived from this overblown novel of high Cs and low behavior in the world of the diva.

The story's main theme is "the gift" of glorious vocal technique, passed on from one generation of singers to the next. It begins when young Ariana Kavalos, Greek-American, is coached in "the gift" by a retired opera star on condition that she eventually do the same for a younger singer. We soon meet Boyd, the homosexual conductor whose marriage to Ariana is arranged for public relations purposes. Then there is Nikos Stratiotis, multimillionaire Greek industrialist, who finances Ariana's career, seduces her on his luxurious yacht, but refuses to marry her. Enter Maggie, socialite widow of an Italian prince, whom Nikos does marry and who pursues fame in the international jet set to the exclusion of all else until Nikos buys her off with an extravagant divorce settlement. Money is no object for Nikos; his driving need is to be sole possessor of anything he wants. When he meets Vanessa, to whom Ariana has bequeathed "the gift," she, too, becomes an object to be acquired.

Lesser personalities also play pivotal roles: an overweight tenor past his prime, reduced to singing in cafes; Ariana's principal rival, a soprano whose voice is artificially maintained with drugs;a venal promoter who steals most of Vanessa's money; Mark, who was Ariana's first love; and Mark's son, Ames, who marries Vanessa.

The plot is studded with suicide attempts, million-dollar necklaces, stays in mental hospitals, alcoholism, homosexual entrapment, mysticism and enough other diversions to keep a soap opera running for years.