The private diary of a hidden princess living a double life in a boring town can never fall into the wrong hands. So, when Princess Sabrina of the House of Valence loses her top-secret journal in class, she has no choice but to return after school hours to get it back and avoid an epic disaster. But is the most rotten school in the world haunted? According to local legend, the Ghost Girl of Mayesbrook Manor stalks the creaky corridors at night. And outside, a pack of fierce stray dogs make sure nobody feels welcome. Luckily, loyal friends Charlie, Awful Agatha and Liam join Sabrina on her terrifying mission. But when they all get trapped after dark by a mysterious security guard, it takes all their courage and ingenuity to outsmart their scary pursuers. Will they make it out alive?