The Midnight Folk is a children's fantasy novel about a boy, Kay Harker, who sets out to discover what became of a fortune stolen from his seafaring great grandfather Aston Tirrold Harker. The treasure is also sought by a coven of witches who are seeking it for their own ends. Kay Harker is aided in his quest by various talking animals, most notably Nibbins the cat, who used to be a witch's cat but has reformed. Kay's governess Sylvia Daisy Pouncer is a member of the coven. The witches are led or guided by the wizard Abner Brown. Kay has various adventures—sailing on the high seas, swimming with mermaids, flying on broomsticks and many more.