Until their father drops dead, two sisters had no idea the other existed and find out the only things they have in common are their names.

Cathy and Cat disagree about how to spend their joint birthday party.

Cat let’s Cathy hide at her house and throws her a party to cheer her up.

Cathy agrees to teach Cat how to ride a bike with disastrous results.

Cathy’s event doesn’t turn out to be the classy, edifying affair Cathy wanted.

Cat and Cathy reel from the news that they have a secret brother - who Cathy just snogged. Marilyn is furious to learn she wasn’t Colin’s only mistress and starts stalking his other lover.