When ""decent, solid, frumpy"" women's rights crusader Amanda Ripley finally procures a flat in Chelsea, financial strain forces her to open her doors to Shelley DuPont, a self-obsessed American would-be actress with a big mouth but, to her credit, an equally big bank account. Also availing themselves of Amanda for a place to live are her slow-witted childhood friend Jennifer Marsh, gullible and innocent with a mental age of four, and the flat's former tenant Candice Valentine, an incorrigible flirt adept at getting her way with baby talk and candy-coated charm. The flat is let by the regal Lady Carlton, an eccentric elderly romance novelist who lives alone downstairs with her constant companion Josephine, a dead dog she has had stuffed.
Candice routinely weasels out of chores and bill paying by evoking pity with tales of an illness that supposedly afflicts her esophagus and prevents her from being able to ""have a proper osmosis."" Unconvinced by her theatrics, Shelley threatens to throw her out of the overcrowded flat for not contributing to the rent, but Candice bribes her way into Shelley's good books by securing her a starring role in a highly suspect low-budget film. Gone with the Wind lends itself to sleazy new levels of interpretation when the girls put on a show for the home video crew.
Frustrated because the flat doesn't afford her any privacy with gentleman callers, Candice takes it upon herself to acquire a social life for Jennifer to get her out of the house more often. The plan backfires when Jennifer is kidnapped and held for ransom, and the others must scrape together 10,000 pounds if they want her back. But will Shelley dip into her savings or sacrifice her beloved sun bed to save Jennifer's life, and can the kidnappers abide a whole hour in Jennifer's company?
Shelley discovers the horrors of Marmite and goes on a diet while rehearsing for a drama school audition. Her failure to simulate a fried egg at the audition sends her spiraling into a suicidal binging frenzy, and it's up to her flatmates to get her back on the health track. Her spirits are raised when she spots her chance to steal a moment in the spotlight at a feminist support group fund-raising event Amanda is hosting at the flat.
Rent is due, and as usual Candice can't be persuaded to produce any dosh. She sinks to new lows to avoid paying up when she fabricates a romance with Prince Andrew, distracting her flatmates from fiscal affairs by awing them with tales of royal intrigue and secrecy.
A council comprised of Amanda's local feminist group has organized a street festival. Distressed that she hasn't been asked to help coordinate, Amanda-- who prides herself on her cultural awareness and politically correct lifestyle-- takes it upon herself to round up an ethnic act that will bring the spirit of Africa to Chelsea.
Lady Carlton's closest friend, her stuffed ex-dog Josephine, goes missing when left in Jennifer's care for an afternoon. There will be no end to Lady C's piteous lamenting unless the girls can convince her that Josephine has ascended to a better place.
The girls receive word that Candice has been rushed to hospital and has died mysteriously. They struggle to determine which of their vindictive practical jokes may have been to blame for her untimely demise, and more importantly, how to destroy any lingering evidence that might implicate them.
Smitten with an electrical handyman, Amanda lures him home to tend to her fuse box. Aroused by the scent of his dirty socks, she is transformed overnight from militant man-hater to Fifties TV house-wife, and she besieges and bewilders the unsuspecting Tom with her feminine wiles. Shelley must teach Amanda the facts about nookie.
After being convinced by Shelley of the value of Capitalist worker exploitation, Amanda orders that Jennifer take a job cleaning offices at the stock exchange to help pay the rent. Amanda and Shelley entrust Jennifer with their complete savings when it comes to light that she's a financial genius at playing the stock market.
Shelley goes on an animal-theme redecorating kick to set the mood for her ""Let's Welcome Shell to Showbiz"" exclusive celebrity party. Amanda reaches the limit of her patience when forced to camp out with Jennifer in Shelley's room while she's on safari in the living room. A vicious slagging match ensues, and Amanda and Jennifer move out of the flat. But they soon find themselves at Shelley's mercy when they're arrested for vagrancy and can't make bail.
Shelley's mother arrives unexpectedly, under the impression Shelley's playing Ophelia at the Palladium when in fact the only part could land was that of a singing tadpole at a grammar school. After learning the truth about her daughter's failure to make it as an actress, Mrs DuPont uses the persuasive power of chocolate to try to coax her into returning to Beverly Hills to marry a dull liver manufacturer. Determined to prove her talents, Shelley crashes a Royal Shakespeare Company production of ""The Importance of Being Earnest"" and literally steals the show.
Lady Carlton wins a new luxury kitchen, but her failure to understand the basics of operating a microwave oven result in a blackout. Mistaking the explosion for nuclear disaster, Amanda and Shelley hole themselves up in a homemade fallout shelter in their front room and send Jennifer foraging for food.
