Sally Potter has been producing little treasures for nearly three decades -- the kind of films that might quietly change your life through some chance encounter late at night on SBS, or at a video store. Completely distinct, stridently political, strikingly unconventional.

The sumptuous Orlando (1992), adapted from Virginia Woolf's novel, sprawls luxuriously across centuries and has a young, otherworldly Tilda Swinton switching genders midway through; The Tango Lesson (1997) is a charged, meta, quasi-musical (Potter herself stars and dances beautifully); while the haunting war-on-terror love story, Yes (2005), is spoken entirely in Shakespearean iambic pentameter.

Now she returns with The Party, a short, blackly hilarious chamber piece, and maybe her most straightforward effort yet. Shot in crisp, chilly black and white, and unfolding in real time over an increasingly fraught hour, it centres on a group of friends who gather at Janet (Kristen Scott-Thomas)'s house, ostensibly to celebrate her ascension to shadow health minister in an unspecified (but we can guess) British party.