THE WELL, starring Pamela Rabe, Miranda Otto. Directed by Samantha Lang. Category IIA. Golden Gateway. THIS psychological drama, directed by Australia's Samantha Lang, puts the sense of isolation that comes from the vast, open spaces of the Great Southern Land to good use. In The Well, Lang is not afraid to draw on the haunting feel of a classic like Picnic At Hanging Rock, where the land takes on a strange, almost malicious personality. But she also adds elements of psycho-dramas like Misery to provide a compelling piece of cinema. One of the best things about The Well is that Lang carefully avoids too much explanation. She isn't afraid to only hint at some things. This helps infuse the action that unfurls - often in a brutal, emotional way - with a taut sense of mystery. Whereas mainstream American films seek to spell out the simplest facts to the viewer, Lang leaves us a few things to piece together for ourselves. Yet it is obvious the director, who based the movie on a book by Elizabeth Jolley, knows exactly where everything is going and how it got there. Essentially, the movie is about the relationship between two unusual but recognisable women. Hester (Pamela Rabe) is an ageing spinster who maintains an isolated homestead in New South Wales. She is very internalised, but is by no means hard and bitter about the way life seems to have marginalised her. In fact, there is an unexpected sense of beauty in her austere existence. When the young Katherine (Miranda Otto), a somewhat flighty 20-something, comes to live with her, Hester immediately takes the girl under her wing. Isolated from any decent male company, the two form a deep bond. They effectively start to live as a couple, although their sexual relationship is kept ambiguous. From the start, their friendship is fraught with uncertainty. Hester is obsessively possessive of Katherine, although she is good-natured enough to temper this. But she resents anyone who could be competition for Katherine's affections, and is sometimes reduced to tears by her jealousy. Katherine, meanwhile, is difficult to pin down. Is she a bit mad? Or is she simply playing up her girlish eccentricity and feline sexual charisma to manipulate the desperate Hester? An inheritance, a dead body and a deep well provide the clues to what's really going on, and the two women's relationship begins to founder. The closing shots make it clear what happened. But for most of the film viewers are kept on the edge of their seats, oscillating between seeing things from Hester and Katherine's respective point-of-views. The Well passes the test of a good thriller, as it's impossible to tell who is really doing what and why. It's not the kind of film that you can guess the ending to, even though it's well written enough to provide plenty of clues. That the characters' pasts - the 'backstory' as they say in Hollywood - are left unclear only adds to the intrigue. We never find out why Katherine has come to live with Hester, for instance, although we are given the smallest of clues. Far from being a sticking point, this omission opens up a whole index of possibilities. Likewise, Hester and Katherine's relationship: although we see them sleeping in a bed together, Lang never explicitly states whether they are lesbian or not. The childless Hester could simply have extreme maternal feelings for Katherine, or even sisterly ones. Again, leaving out material that today's Hollywood producers would have deemed crucial helps to fire up the mysterious happenings. The Well is director Lang's debut movie, and as such is not flawless. The great sense of isolation she sets up disappears about two-thirds through when the psycho-drama element is given full reign and more personal motives take over. Unfortunately, here it looks like Lang has studied Stanley Kubrick's The Shining too many times. A sequence in which Hester finds herself tied to a chair with the long braids of her own hair is a bit at odds with the rest of the film. But at least Lang has done her homework well, and the scene gives a good approximation of that deranged The Shining feel. Still, it's a small gripe in what is generally an impressive directorial debut. First-timer she may be, but she seems to understand one important thing many experienced film-makers would do well to remember. Producers often want films made insultingly clear. But as Lang ably demonstrates, there is nothing as powerful as holding a little back.