When their father's work brings them to Fremantle, the Thomas children find themselves living next to a very spooky house, complete with a turret. Eight year old Becky thinks she sees a witch's face at the window and after all, Becky is a trained witch spotter... Of course the rest of the family knows there's no such thing as witches. But when the children's sitter turns out to be one of the mysterious old ladies living next door, they begin to have doubts when strange things start to happen. And what happened to Captain Prosser who so mysteriously disappeared? And will they discover the secret of the witch's egg?