Amazing Grace : SCHOOL FOR THE BLIND, <i> By Dennis McFarland (Houghton Mifflin: $21.95; 287 pp.)</i>

At 73, Francis Brimm has retired from wandering the world as a celebrated news photographer, and returned to Florida’s Gulf Coast where he was raised and where his older sister, Muriel, still lives. He had imagined catching up on the slow pleasures his airy career left him no time for: gardening, preparing meals and savoring the fullness of days passing.

None of these answer his restlessness. Instead of cooking he eats fast food. Having bought seed and fertilizer, he wonders: Why not pay a gardener? Instead of mellow self-reflecting he stands at the window at night, hoping to catch a glimpse of a beautiful neighbor naked. Lastly, a vision keeps appearing on his bedroom ceiling of a terrible wartime scene he had photographed. A French woman collaborator is hustled, shaven-headed and holding her German-sired baby, through a jeering mob. (It is one of the Second World War’s most reproduced images; it is odd to find it attributed here to a fictional character.)

Muriel, who balances surface practicality with religious devotion, gets him to consult their new Episcopal rector. Francis is taken aback to find that she is a woman. He is even more taken aback when she advises him to shut his eyes and try to become the woman in his vision. When he objects that this is therapy, not religion, the rector cheerfully offers to go into the history and theology of visions if that will make him feel better. The spiritual, it seems, is optional.

It is one of the more telling scenes in “School for the Blind.” Dennis McFarland, author of “The Music Room,” has written a novel that teeters on the edge between the immanent and the mundane. The story of Francis and Muriel, nearing the end of their lives, has one foot delicately poised in the psychological and the other in the mystical. It is an interesting balance but an uneasy one; reminiscent in some ways of the Anglican explorations in the theological detective stories of Charles Williams and the theological science fiction of C. S. Lewis.

Francis’ vision will ultimately reveal to him the real purpose for which he has returned to Florida: not to retire but to die. And, once he accepts this it will turn out to be his salvation. A life spent in evasion--photographing history is the path of the voyeur, in McFarland’s image--will become a dying in which life is modestly embraced.

At the same time, Francis’ return sets off a series of events that will produce an equivalent self-deliverance for Muriel. Her cheerful busyness and assiduous church-going are a different kind of evasion, stemming from a common history. The siblings, as children, had been through a shocking ordeal of abuse--she as victim, he as helpless witness--which both have hidden from themselves ever since.

McFarland treats the twin ordeal and redemption of brother and sister in a style that embeds an essentially providential allegory in a novel which, though dramatic, moves by largely realistic narrative and psychological detail. For example, the persistent questions that Francis begins to ask about their childhood are one of the instruments that contribute to the sensation, as he puts it, that “the ground has begun to shift beneath our feet.” But they are explicable simply in terms of the mental and emotional restlessness of an old man suddenly confronted with nothing to do.

The same restlessness makes it perfectly plausible that he should awake at night and go for solitary walks. On one of these he comes upon a dog digging bones out of a golf-course sand-trap. They are human bones, he realizes, and notifies the police. The subsequent events run more or less along the lines of a detective story. At the same time, though, the disinterment will become, both symbolically and in fact, the revelation of what Francis and Muriel have for so long forgotten.

Day by day the lives of Francis and Muriel proceed in prosaic, sometimes comic detail. He tries to busy himself; she is busy with meetings, piano duets and book study, much of which is conducted with two aging friends. The friends are attentive and irritating; there is nothing wrong with them but they exasperate Muriel more and more. Her life has begun to shake with strange portents. An old friend seems deliberately to look away when Muriel passes (he was distracted); crossing a footbridge she sees a bowler hat in the water (it is an otter). And in her house--her childhood home--the entire upstairs, where she and her parents once slept, seems haunted. Looking into the mirror she sees other faces.

McFarland impressively blurs the lines. Is the charged, sinister light that bathes the Florida landscape an illusion of two aging minds, one of which--Muriel’s--is on medication? Is it the psychological pressure of an old secret asserting itself against a septuagenarian’s diminished power to armor the present against the past? Or is it the onset of a spiritual ordeal with religious implications.

The immediate ordeal is Muriel’s. The bones turn out to be those of two schoolgirls, raped, killed, dissected and buried. The killer writes anonymously to the local newspaper. He tells of horrifying sexual and physical abuse by his father in a letter that McFarland has brilliantly devised to reflect poignancy and madness. Reading it propels Muriel into her own suffering past; she goes through a weeklong collapse that manages to suggest both clinical breakdown and a dark night of the soul. For his part Francis suddenly recalls what the French mob shouted at the woman: “Angel of Death!” It is, retrospectively, something more than a natural presage: He learns that he has a fatal blood disease.

The book’s last part contains a series of reconciliations and deliverances. Muriel takes in the dying Francis; she also takes in Deirdre, a young woman who had worked for her and whom she had fired for her turbulent way of life. Pregnant, Deirdre becomes for Muriel a means--the phrase is a little too smug--”to work out my salvation.” She is also a form of angel. Redeeming Francis from his lifelong isolation, she and the dying man fall deeply and chastely in love.

McFarland has woven together the natural and religious with considerable intelligence; the result, though, is more striking than convincing. His removed, elaborately Jamesian diction can be a drawback, although he balances it amusingly with the querulous, down-to-earth rhythms of his aging protagonists. Childhood sexual abuse is a risky device for a novelist, not because it is shocking but because it can be a pat explanation for almost anything. McFarland avoids that risk; patness, on the other hand, clouds his religious currents. With exceptions--Francis’s happy deathbed is poetically convincing--the author’s transcendental is sentimental; his divinity is abstract and unctuous at the same time.