The self-contained ground floor flat at 33 Highgate Avenue becomes vacant when the Rush family's sitting tenant, elderly Arthur Fenston, dies. After the funeral his relatives arrive to pick it clean of his possessions. While Jacqui and Susan plan a party [to celebrate the simple fact that they can have one without the police being called], their father Dudley sets his mind to finding a new tenant. With a little help from their friends, David and Angela Jones, the girls hatch a plot to secure the flat for themselves.