It's interesting that Anna Murdoch, a woman who must constantly be pigeonholed as "the wife of newspaper magnate Rupert Murdoch," should frame her flawed but promising first novel around a pair of sisters struggling to establish separate identities -- in this case separate from their mother. There are added factors, of course, but at the bottom of the whirl of jealousy, hope and longing that propel Murdoch's plot lies the always tricky question of how much we can define ourselves in terms of others and whether love, be it sexual or maternal, is a way of finding the answer or merely another part of the problem.

Betty Beauchamp, the pivot of all this speculation, appears at first glance to be little more than a slightly dithery, disorganized divorce' sliding not too gracefully toward the tail end of middle age. Established in a rickety cottage on her son-in-law's barren sheep station in New South Wales, she looks forward to a Christmas reunion of her far-flung family. Her brusquely efficient and childless daughter Liz, with whom she spars incessantly, lives just down the hill. But her other daughter, Josie, is returning after a long absence from New York, accompanied by a 12-year-old grandson whom BB, as everyone calls her, has never seen. And to round things off, BB has engineered the appearance of her own mother, Daphne, an elderly English widow who long ago gave BB up for adoption.

Clearly the holiday festivities at Tiddalik Station will be no ordinary gathering. And as the characters circle round each other, the atmosphere becomes as dry and brittle, as tension-filled, as the drought-parched land whose searing heat pricks at them "like pins."

Gradually, we learn of BB's profligate past, her neglect of her children, and their resulting conviction of her inability to love. In Josie's case, this brings the terrifying fear that the lie she has been living, the secret she wants to share, and the self-indulgence it suggests, mean she is not better than her mother. But for Liz, who became a mother to Josie when BB abdicated the role, love has evolved in reaction to BB's dreadful example, yielding a painful blend of yearning and self-sacrifice, a stern denial of the emotions that once linked -- and may yet link -- her handsome husband and her newly returned sister, who is now a stranger.

For Liz, everything cannot be "stripped bare, exposed, left pitilessly without water like this land she loved." Her choice of words is no accident, since her moods are reflected in the landscape, as are those of the other characters. And so it's not surprising that the climactic scenes, involving a hellishly revelatory Christmas dinner and its aftermath, are punctuated by a ferocious drought-breaking rainstorm, and the resolution that follows is as much a product of external forces as it is of any conscious actions on the part of the main characters.

This points up both the strengths and the weaknesses of Murdoch's novel, for although she succeeds beautifully in conveying the look and feel, even the smell, of the world she is depicting, her hand is less sure when it comes to guiding its people. Liz and Josie are fully fleshed, even in their inarticulate gropings, their contradictions. But BB, instead of becoming more complex and provocative, merely turns into an ogre, a fanatical "pragmatic Christian" whose incipient madness offers as convenient an escape from explanations as does the final fiery twist of the plot, from which the survivors can make an all too tidy exit.

But if the plot creaks in places, and its phrasing occasionally takes on a breathless, strung-out rhythm, it is redeemed not only by the finely drawn perceptions of Liz and Josie but also by some first-class scenes. In one, the newly arrived Josie is entertained at lunch by her mother and grandmother, and the conversation between the three women, who know so little about each other magically acquires a fragile coziness, an intimacy that is moving because we know just how transitory it must be.

In another, the two sisters sit beside each other on the veranda of Liz's house and in a single silent gesture a certain understanding, a certain peace, is acknowledged. Watching her son walking up the hill to join them, Josie "wished with her whole heart that her mother BB could have had this grace; the knowledge really to see what was around her, to treasure a minute like this."

It is a vision that will, one hopes, return in Murdoch novels that are yet to come.