THERE HAVE been vacations pledged to great books; there have been vacations given over to trash: neither extreme is satisfactory. War and Peace and its like are not beach reading. Those 1,500-odd pages grow gritty with sand, sodden with sun cream. Beneath the virtuous sense of the undertaking runs the guilty feeling that Tolstoy would not approve this setting. But far worse is the guilt of returning to town bloated with a two-week diet of literary junk-food -- unthrilling thrillers, cheap romances, and the like. The best vacation solution is the literary middle ground: some good solid books -- that biography you've been meaning to get to -- and some "good reads."

The White Dove is just that -- a good bad book, a long, engrossing, melodramatic, historical romance. It does not measure up to the great bad books, classics like Brideshead Revisited and Gone With the Wind, which shape our mythologies and alter us forever. But then, such books are truly rare. The White Dove draws on the world of Brideshead and is redolent with the feeling of Gone With the Wind. If it is not in their league, it is nevertheless a delicious read. I gobbled it up whenever I could, wishing I were on a beach, free to prolong the banquet, instead of in the workaday world obliged to nibble a chapter here, two chapters there.

The White Dove spans the interwar years, telling the stories of two families -- one rich, English, declining aristocratic; the other poor, Welsh, struggling working-class. Thomas give a fine account of the difficulties of mining families in the Rhonnda Valley -- the frightful dangers of pit work, the hardship of pit closings and unemployment. But the stories do not have equal time; the aristocratic Lovell family commands more of the novel. Poverty affords less freedom and variety, and in a novel like this, variety means more interest. The Lovells complain of the constraints of upper-class convention, but in the course of the novel we see these conventions decaying, and the Lovells themselves up to all kinds of things. We see Amy, the heroine, dancing with the Prince of Wales, attending a Communist rally, rejoicing in her lover's gift of diamond earrings, nursing the Republican wounded in Spain. Thomas presents the Lovells' world as opulent, empty, but also vaguely enviable. Throughout the book Amy makes constant retreats from the hard nursing life she has chosen into little luxurious laps. Some are faintly incongruous as when she takes her wounded working-class lover from the frontlines in Spain to the grandest hotel in Biarritz.

The Lovells' world is always opulent, untouched by the Depression, but at the outset it is not empty. In the opening chapter we see them for a brief moment in their high aristocratic state of unbought grace. It is July 1916, tea time on the lush green lawns of Chance, a 16th-century country manor. Lord Lovell fondly helps with the tea things, for his second wife, a beautiful young American heiress, is tired at the end of pregnancy. Two prettily-frocked girls eat cakes. A cloud of servants hovers discreetly in the wings. Then the idyll shatters. A telegram arrives: Lord Lovell's beloved heir by his first marriage has been killed in France.

The family comes apart. Lord Lovell cuts himself off from his wife and children, taking instantly against his newborn son, retreating behind a wall of angry grief. Adeline consoles herself for her lost husband -- first with her children, particularly her adored Richard, but then, gradually, with lovers. The two sisters, Isobel and Amy, find themselves growing up under the care of Bethan Jones, their devoted maid from the Rhonnda. THE WHITE DOVE, following in the line from Jane Austen to E.M. Forster and D.H. Lawrence, is a novel of two sisters. Isobel and Amy, particularly Amy, center the book, and Thomas handles deftly their contrasts and parallels. Isobel, the dutiful, conventional older child, makes the seemingly perfect match with a rising politician. Amy rebels: she goes to Communist Party meetings; she determines to make her life useful by becoming a nurse.

However, Peter, Isobel's husband, turns out to be less than perfect -- a Nazi sympathizer and a sexual sadist who drives his wife to collapse. Amy seems more fortunate in love. At a Communist rally in London she meets the Welsh miners' union leader Nick Penry, whom she finds hostile but magnetic. Later she finds him again at Chance: the Depression has forced him to leave Wales, and he has taken a gardener's job to feed his wife and child back home. At Chance, Amy and Nick become lovers, and eventually she follows him to the Spanish Civil War.

The passionate, rebellious peer's daughter, the Lawrentian working-class lover -- these are familiar types. One of the comforting charms of The White Dove is that it is not original: it embraces the several genres of which it partakes. (This, however, is what distinguishes it from great bad books, which unite the conventional and the original.) One can recognize the pieces, yet still applaud Thomas' skill in assembling them. A few of the minor characters are especially well drawn. Adeline Lovell, an adoring mother and unabashed hedonist, and Richard, her flamboyant homosexual son, whose roman a clef scandalizes London and his father, are particular favorites.

But of the main characters in the novel, one can only say truthfully that one cares less about them than about what happens to them. This is not simply criticism: Thomas has real narrative talents which make the novel a page-turner. Catastrophies abound, at least one a chapter. There are countless deaths, a marital rape, an attempted infanticide, a suicide, and so on. All these events are gripping; several, most notably the mining explosion in the second chapter and the battle scenes in Spain, are powerfully written. Thomas is also fond of coincidence; in a sense she has to be if she is to braid two remote worlds together. Bethan Jones just happens to come from the same town as Nick Penry, where her mother, the town midwife, just happens to have delivered Nick's retarded child. This conveniently allows Amy to pay a visit and see the difficult reality of her lover's family situation.

But one must not cavil. Coincidence, after all, is in the best Dickensian tradition, and gives the little frisson one wants in a summer book. The White Dove is a delicious example of the Art of the High Obvious -- perfect for the beach, the mountains, or, heaven forfend, a summer cold.

Kathleen Emmet is at work on a book about Americans in Paris after World War II.