Weirdness, particularly sexy weirdness, is a trademark of French film director Francois Ozon's films. In the musical melodrama Eight Women, an Agatha Christie pastiche featuring some of France's most beautiful actresses, he has Catherine Deneuve tusselling on the floor in the embrace of her arch enemy played by Fanny Ardant. In black comedy Sitcom a demonic lab rat sets libidos into overdrive - even incest is in. In Criminal Lovers it is Hansel and Gretel styled S&M fantasies.

This unusual English language drama, set in a French country house with a swimming pool, is relatively tame. There is a strong sexual undertow throughout, but this slow-building mood film relies less on eccentric plot turns, although not without dispensing with them altogether.

Charlotte Rampling plays a taciturn and prickly author, Sarah Morton, living in rainy London and looking after her elderly father. In spite of her successful career, she is bitter and fed up writing her detective thrillers. When she complains to her publisher, John (a debonair Charles Dance) that he doesn't nurture her like he used to, there is the suggestion of a romance that has gone off the boil.

On John's suggestion, she moves to his house in France to relax and write. In the quiet warmth of the French countryside she blossoms: the words flow, we see her enjoying trips into the local village and she even starts flirting, hesitatingly, with a hunky waiter at the local cafe.

However, her peace is upset when John's French-English daughter Julie shows up unannounced one night. Luscious Ludivine Sagnier plays the randy young teenager who hobbles in high-heeled sandals, skimpy shorts and little else by the pool by day and keeps Sarah awake having loud sex with a different man from the village each night. The swimming pool provides a metaphor for their differences. Early on Julie declares that she loves swimming in the pool, to which Sarah calls it "a cesspool of bacteria".

Initially Sarah is tight-lipped and frosty, irritated by Julie's attempts at friendliness, her hedonism and her unabashed sexuality. But after initially observing Julie with cool disdain, Sarah's curiosity gets the better of her. Julie even works her way into Sarah's fantasies, as well as into her novel.

In such a self-contained film - there are few visitors to the house - these two actresses are able to shine. Both are highly watchable for different reasons. Sagnier is a combustible mixture of sexy impudence, youthful rebelliousness and vulnerability. Rampling, 58, gives a riveting performance, with sharp-tongued put-downs and suppressed sensuality.

Ozon teases us with the possible ways in which the relationship will play out, deliberately leaving many questions about each character's past unanswered along the way. It is funny, sad, surprising, and mysterious. Events occur slowly, almost imperceptibly, which may explain why Ozon saw fit to throw in the sudden, almost perfunctory plot twist in the latter part of the drama. Still, if the denouement seems an Ozon incendiary device, the rest of the film smoulders brilliantly.