The programme was a comedy with its premise being loosely based on Robert Louis Stevenson's Gothic 1886 novella, Strange Case of Dr Jekyll and Mr Hyde.
Olivia Hallinan plays an intelligent schoolgirl named Julia Jekyll who makes a special drink called an elixir for a science project, but two school bullies named Nicola and Sharon known as "The Blister Sisters" sabotage her experiment by adding a hair restoring formula to it.
When Julia sips the drink during a demonstration, she turns into a huge hairy monster named Harriet Hyde that scares the living daylights out of most of the people around her, even though she is harmless and friendly to most.
However their next-door neighbours, Jason and Mona Jitter, a neurotic couple who spent most of their time at a therapist's, were terrified of Harriet and had numerous unfortunate encounters with her.
A businessman called Tim Tok Lim is interested in Julia's elixir, and is invited to the Jekyll's home for dinner to test it.
The Jekyll's new cleaner, Mrs Figgis, steals valuable items from the family, including Jerry's prized bravery award.
Julia and Harriet are invited to come to tea by Mr and Mrs Rocket, Jason and Mona Jitter and her parents.