Like ''Lamb,'' MacLaverty's previous novel, ''Cal'' is a story of sacrifice. Shamie McCrystal and his 19-year-old son, Cal, are the only Roman Catholic family left in their estate in the Protestant north of Northern Ireland. A hard-working, honest man who spends his days in the abattoir, Shamie refuses to move out or to give in to political pressure and personal threats.
Cal, unable to stomach the blood and stench of the slaughterhouse, is on the dole. He kills time smoking, listens to records. Occasionally he visits the library, where one day he notices a new woman behind the checkout desk. Her name is Marcella.
MacLaverty pauses: ''He studied her face, trying to read into whether or not she was the Marcella. He could not take his eyes off her, not because of what she was but because of what he might have done to her.''
Cal, you see, had been bullied into working for ''the Movement'' by a gruff schoolmate named Crilly. He then served as an accessory to the murder of Marcella's husband, Robert, a Protestant and member of the Police Reserve.
A year after the murder, Crilly solicits Cal's help, but Cal protests: ''I want out. . . . I have no stomach for it.'' To which Crilly replies: ''This is war.'' Cal agrees to be Crilly's getaway man, but ''only for funds . . . just this once.''
Cal keeps his work for ''the Movement'' a secret from his father. During the day he toils on a farm owned by Mrs. Morton, a liberal Protestant. She is also the mother-in-law of Marcella, a Catholic, who lives there with her.
After dire threats and physical confrontations, Cal and his father are burned out of their home. Cal finds refuge in an abandoned shack on the Morton farm. His desire to confess, to see Marcella, speak to her, touch her, becomes an obsession. He spies on her from his hideaway until Mrs. Morton spots a light in the cabin and calls the police. Hearing Cal's story, she takes him as a tenant.
MacLaverty, who was born in Belfast and now lives in Scotland, proved himself an accomplished artist in ''Lamb.'' He has a painter's feeling for atmosphere and detail and a lyrical, poetic voice. His narrative here is punctuated by moments of stillness, flashes of insight.
But he is really a better writer than storyteller. The plot of ''Cal'' is contrived, too neatly worked out to be fully convincing. The relation of cause to effect is too simple, predictable, and the transition from one emotional or psychological state to another is too quick.
Cal effectually assumes the role of Marcella's husband. He learns of her unhappy marriage; he becomes her lover; he even wears her dead husband's clothes. His inability to tell Marcella the truth, to share his guilt, is a reflection of his inability to choose, to act. But ''Not to act,'' Crilly reminds him, ''is to act.''
One day in town Cal runs into Crilly planting a bomb in the library stacks. ''Government property,'' Crilly explains. ''Orders is orders.'' Crilly intimidates Cal into going back to his house, where he charges him with desertion. ''The next step is to become an informer,'' he warns. ''You know the penalties for that in any other army in wartime.''
Parts of the novel seem derivative. The scenes of Cal's voyeurism, for instance, echo Sherwood Anderson's ''The Strength of God,'' and Cal's physical relationship to Marcella is reminiscent of that between Lady Chatterley and her gamekeeper, Mellors.
Still, the novel deals with important moral, religious, and political issues, and its effect is moving. MacLaverty portrays Cal as a victim of history and of his inability to choose, though he comes to recognize this as a choice in itself and takes responsibility for it. His spiritual growth can be seen as following the traditional pattern of progress toward sainthood, which culminates in illumination. Cal, who dreams of crucifixion, is sacrificed for his country. MacLaverty uses his life as a metaphor for the Ireland that is so sharply torn between conflicting religious and political beliefs, and his sacrifice is peculiarly Irish.
''It is not those who can inflict the most but those that can suffer the most who will conquer,'' said Terence McSwiney, a member of the IRA and Sinn Fein lord mayor of Cork, who died on a hunger strike at the height of the Anglo-Irish war more than 60 years ago.
''I feel sorry for Ireland,'' Marcella says at one point. ''It's like a child , only concerned with the past and the present. The future has ceased to exist for it.''
MacLaverty's sympathy for his country conveys his sense of distance from it, and from a part of his own past. But perhaps it is this distance that has enabled him to put the tragedy of Northern Ireland today so poignantly in perspective.