In London during the 1980's an upper-class husband is having an affair with a snobby married woman, his wife in turn has an affair with a lower-class detective, who she has also hired to find any incriminating evidence on her husband.
Upper-class geek Steve (Berkoff) is having a relatively pervy affair (lots of animal impersonations but little sex) in Belgravia with Helen (Collins), a sophisticated slut with centuries of wealth behind her. Steve's nouveau riche wife Sybil (Collins encore, taking both accent and character name from Fawlty Towers' Prunella Scales) is having unsatisfactory sex in Cheam with Les (Berkoff with a 'tache), a private eye she has engaged to do in her horrid hubby.
Once these characters are established, you expect some plot development, but none of these people ever does anything, so the film, like their relationships, goes nowhere at a very slow pace. A succession of sketch-like scenes, ranted in doggerelish rhyme, show either the rich being horrible or Syb and Les seething with class resentment.
Obviously theatrical in its origins, this is mainly a showcase for Berkoff's trade-marked grotesque style, with Collins enthusiastically joining him in facial contortions or verbal tics. The central conceit that "rich people are slime" is hardly fresh territory for a satirist and Berkoff's Steve is an appalling creation, though maybe with someone else directing he could rank as one of the great monied monsters. But Decadence sadly dwindles into a succession of buggery, sex, farting, puking, crapping and whipping scenes. And beyond Michael Winner cameoing as a nasty Tory clubman and the shock value that comes with knowing that Joan Collins would consent to say the things Berkoff puts in her mouth, this offers very little to keep you glued to your seat for what is, in reality, two rather uncomfortable hours.
This film's supposed trump card is the joke of having Steven Berkoff and Joan Collins play a married couple as well the strangers they are having affairs with. Although both put in amusing performances if the concept doesn't have you laughing already the