Olivia Hallinan plays a schoolgirl named Julia Jekyll who makes a special drink called an elixir for a science project, but two school bullies named Nicole and Sharon known as "The Blister Sisters" ruin her experiment by placing all kinds of dangerous things in her drink including a hair restoring formula. 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. The effects usually wear off after a while but unexpectedly keep coming back. Julia's best friend and fellow student from Rocket Academy, Edward Knickers is the only one who knows her secret and she has hard work trying to hide it from her parents, next door neighbors, the teachers and all the other fellow students whilst she tries to find a cure. Teachers at the Rocket Academy were the jolly headmaster Memphis Rocket and Lester Blister, the Blister sisters' cruel uncle.