In a new world of interchangeable gender roles, Francois Ozon's The New Girlfriend, an adaptation of an 1985 Ruth Rendell short story, at first seems to be on the pulse but then lets the entire enterprise descent into melodrama. The 5x2 director doesn't help things by setting up one kind of movie before becoming something else.

Ozon takes delight confusing in his opening salvo. His first shot is an extreme close up of a pair of women's lips as lipstick is applied, followed by a wider shot of her face as mascara and makeup are added. Then she's dressed in a wedding veil before being placed in a coffin. So this is a funeral then, and her best friend Claire (Demoustier) gives a touching eulogy from the pulpit. It's here that Ozon segues into a terrific backstory sequence where a young Claire and the now-deceased Laura (Le Besco) enjoy a tight friendship. It's all very serious, very arty, very touching.

Then there's a switch in tone and things silly.

Growing up Claire (Demoustier) and Laura (Le Besco) were inseparable, with a whiff of sexual attraction in the air. Laura then marries David (Duris), and they have a daughter, while Claire gets hitched to Gilles (Personnaz). But then Laura dies young, leaving a giant Laura-shaped hole in Claire's life. Calling on David and the baby one afternoon, the grieving Claire is shocked to find David in drag. Protesting that the crying baby is soothed by the appearance of her 'mother', a shocked Claire finds herself first drawn to this persona David calls Virginia and then becomes attracted to 'her'...

The sexual dynamic keeps things interesting as Ozon explores this complicated subject. Claire becomes attracted to David but only when he's Virginia, and only because Virginia looks like Laura. She later tells Gilles him that her lipstick on him is 'sexy' and that he looks good in her scarf. Meanwhile, David maintains that he has no interest in men, but likes the way men look at him when he's Virginia. Ozon touches on the origins of David's cross-dressing desires (he keeps his mother's old fur in the wardrobe) but doesn't explore further. There's a lot here.

But mixing playfulness with melodrama doesn't work as well as it could here. The touches of farce - the frantic removing of the lipstick when David's mother-in-law stopping by unexpectedly, accidentally sitting in a feminine way, the makeover montage – feel parachuted in from Mrs. Doubtfire. The final act pushes The New Girlfriend from melodrama into downright absurdity.