Sally Potter's pitch-black comedy The Party begins in the London home of Janet, a liberal politician (Kristin Scott Thomas) who's just won an important position at the National Health Service, and so is hosting a bash for friends.

It's her party, and she'll cry if she wants to, but why would she want to?

To spill the beans would spoil whatever perverse pleasures can be found in watching the rapid disintegration of what has been envisioned as a cozy, civilized celebration. It begins with Janet in her kitchen, preparing a meal for her guests, making a great show of being the kind of woman who can have it all and do it all – sticking bread in the oven, answering congratulatory phone calls, etc.

In the living room, though, are signs of trouble. Her academic husband, Bill (Timothy Spall), is catatonic, sitting open-mouthed in a chair, as if in a state of shock unrelated to his wife's sudden success. He barely moves as guests arrive. First is Janet's best friend, a caustic American woman (Patricia Clarkson). She congratulates Janet and insults everyone else, including her boyfriend, a new age German quack (Bruno Ganz) on hand to provide useless advice about medicine or psychology.

Other guests/targets include a banker (Cillian Murphy) whose wife has been delayed, and Janet's acquaintance Martha (Cherry Jones), whose partner (Emily Mortimer) arrives a bit later.

The movie is short, and it's pace is kept brisk by successive revelations — every character has a secret, some more than one, and some of these secrets intersect. I won't reveal them, but it's fair to reveal that Potter's title has a double meaning. What's wrong with Janet's party is related to what's wrong with Janet's political party. The politics are never spelled out, but the movie plays like a farce about political complacency written by Potter in response to Britain's Brexit vote, and the results of the presidential election across the pond.

Frantic turns of fortune force characters to face crises that test the sincerity of their public policy pronouncements. Potter paints a portrait of insincerity and hypocrisy, and takes an unflattering look at what appears to be a liberal political elite — it's not always as bleakly funny as you want it to be, but it's certainly brave, given the audience likely to be watching it.

Potter has assembled a good cast that gives the claustrophobic material some air — the theatrical drama is set in just a few cramped rooms, including the loo. Potter also chooses black and white, suggesting stark contrasts that blend, like the viewpoints of the characters, into shades of gray.