SWEETHEART; A Novel of Revenge. By Andrew Coburn. Macmillan. 275 pp. $16.95.

IT BEGINS in the dead of winter. An elderly couple are tortured to death on a frigid Massachusetts night by two countryboy thugs looking for money.

As the lads' luck would have it, they've just killed the parents of a Mafia kingpin in Boston. As our luck would have it, that's the start of a tough, lean novel of revenge, ambition and human frailty.

As dark and dense as Francis Ford Coppola's vision of The Godfather II, Andrew Coburn's book wastes neither motion nor emotion, gliding through the shadows that lap at the players' lives.

The mafioso -- trapped in a world he built, a way of life and death that grants few graceful retirements -- wants his parents avenged. The FBI man -- an obsessed and cunning puppeteer who glories in the "blood sport" -- wants his name in the papers and the kingpin and his henchmen destroyed. The state police lieutenant -- code-name "Sweetheart" and the key to the trap -- wants his wife back, or thinks he does. The other crippled characters have their own soiled dreams.

So, who gets his?

Well, let's just say there's death aplenty in this quicksand land of matter-of-fact evil. And pleasure aplenty for fans of crime novels. THE BLOOD SEED; A Novel of India. By Andrew Ward. Viking. 576 pp. $17.95.

THE YEAR of India isn't over yet. And that's cause for celebration, since it brings us Andrew Ward's The Blood Seed, a handsomely crafted and beautifully written novel spanning the 90 years immediately after the bloody Sepoy Rebellion of 1857.

Unlike so much of the recent torrent -- from film's A Passage to India to TV's Jewel in the Crown to a spate of novels -- here the land and its lives are seen through the eyes f an Indian. British relations with Indians are not the crux. The Raj is simply another elemental force, like the monsoon, to be acknowledged and accommodated.

For a reader unfamiliar with India, it's hard to gauge whether the author, an American, has been faithful to the time and the people, but everything feels right. The language, the scenes, the details are precise and elegantly evocative.

The central device of the novel, masterfully handled by Ward, is a manuscript given by an old Indian servant to his departing British master. It is the servant's life story, which opens in his village of Cawnpore -- site of a massacre of the British by rebellious Indian troops and then an eye-for-an-eye retaliation by British troops -- and follows his long struggle to discover his identity and solve the mystery of his unknown father.

While the seismic shock of the massacre travels the length of the novel and gives it much of its power, the book's ultimate strength lies in its writing:

"Staring into the fire, I promised my mother that I would stay awake until morning. But it was a child's vow and quickly broken. The forbidden flames put me into a trance, and through the night I ferried back and forth between consciousness and sleep, so that to this day I can't disentangle my memories of that night from my dreams," the servant remembers, relating the horrific night of his mother's cremation when he was but a boy. "You would think that when I heard paper crackling high above me and looked up to see my mother hovering over the river in the bow of a golden kite, waving down with a sad smile to her earthbound son, I must have been dreaming; and that when her skull came loose and rolled down from the pyre's summit, spewing sparks at my feet, I was probably awake. But on that night my mother was burning and I had set her on fire, and if that was true then anything was possible: even the kite." THE LINZ TATTOO. By Nicholas Guild. McGraw-Hill. 333 pp.

THE LORD staked out vengeance as His turf a few millennia ago, but the copyright must have expired, because here's another novel of revenge, this one a diverting thriller set in Europe not long after World War II.

Inar Christiansen, a Norwegian with music in his soul and murder on his mind, is rattling about as the Lone Norseman of the Apocalypse, systematically tracking down members of the Waffen SS brigade who butchered his parents. He prefers to strangle them with the catgut from his Guarneri cello, but other weapons will do in a pinch. Col. Egon Hagemann is next.

Members of Israel's newly formed secret service, the Mossad, are also after Hagemann, but they want him alive, at least until they can get their hands on the deadly secret he hopes to deliver to the Arabs. A survivor of a concentration camp, a young Jewish girl used and abused by Hagemann there, serves as bait.

It makes for an entertaining plot, and that's crucial, because, in addition to vengeance, the plot has to cover a multitude of other sins -- namely Nicholas Guild's failure to create a sense of person or place and his inability to deal successfully with the Big Issues he insists on discussing: Love, Hate, Death and Evil. In particular, his tangled efforts to understand and explain the Nazi atrocities -- "The war had been such freedom as perhaps no man should have" -- sometimes come perilously close to being an apologia.

The dialogue has its own rough spots: Czech Jew, Norwegian, and German officer all talk exactly the same way.

But whenever things start to bog down, there's always that high-powered plot to pull us out of the sloughs. And besides, whoever promised us a prose garden? THE KEYS OF THE CITY. By Michael Pearson.Warner. 388 pp. $16.50.

OH, THE THINGS she does for love -- and money. She is Quincey, a smart and exceedingly resourceful young woman determined to make her way and her mark in the all-male world of high finance at the turn of this century.

Her battleground is "the City" -- the financial district of London -- and the keys to it are her intelligence, charm, perseverance, cunning and -- yes, it must be said -- her body. After considerable introspection on that last matter, Quincey decides she probably should use every tool at her command.

It's all the stuff of the easy, breezy romance novel, with a bow here and there to tougher books like Sidney Sheldon's Master of the Game. The crises -- deaths, accidents, financial setbacks, confrontations over control of the family bank she has married into -- come and go with the steady reliability of Swiss trains. Ditto for the sex scenes, which have some steam but not too much heat.

Sometimes you can't help but stop and hoot. Purpler than this, prose does not get: "I had never known a union with him of such intensity -- or even glimpsed the level of ecstasy to which we rose in the early hours of that strange morning. The experience was totally basic of the earth, yet at times I lost touch with my body, knowing a duality of self like some Eastern sannyasi in the heights of spiritual elevation. Time lost its meaning. Hours could have passed or mere minutes."

Which makes The Keys of the City about right for lunchtime in the park, or the subway ride home. THE SET-UP. By Vladimir Volkoff. Translated from the French by Alan Sheridan. Arbor House. 397 pp. $16.95.

ARNAUD de Borchegrave and Robert Moss broke the ground with The Spike. And now Vladimir Volkoff is turning the same soil to expose Soviet agents dedicated to the subterranean destruction of western democracy.

The thesis of his "Set-Up" is that the Soviets hope to capture the West without firing a shot: Through disinformation and agents of influence in publishing and other arms of the media, they plan to mold public opinion and eventually paralyze any opposition. The tactics, as one character explains, are based on the assumption that "unlike revolutions in the past, modern revolutions are conducted against the majority and not against a minority."

In this case, the target is France, and the agent of influence is a literary agent, the son of a White Russian emigr,e whose dying wish was that his flesh and blood one day return to the Motherland in his stead.

The novel opens with a beautiful, deceptive simplicity ideally suited to the father's naivet,e and closes with a terrific rush. But in between are about 280 pages of mighty tough sledding.

In those pages, we often find a classroom exercise masquerading as a novel, so intent is Volkoff on using fiction to deliver his warning and detail the threat. There are discourses on Marxist dialectics, intricate explanations of the strategy and techniques of disinformation. And some interesting shop- talk speculation that God could be the ultimate manipulator, "the Great Contriver"; that Christ's cry on the cross -- "lama sabacthani" -- came from the anguished realization that he had been tricked by a superior. All this in an expansive prose style modeled on the Russian and translated from the French.

The novel's greatest problem, however, lies with the specific schemes described. What is supposed to be chilling is simply confusing. In this whirlpool of user and used, it's impossible to see how the subversion is working.