The Myra twins, Pixie and Angel, are on the most boring holiday ever in a cramped caravan on the Sunnyvale campsite. To add to their misery, Gran is having a whole lot more fun than them, until the messenger arrives. In five days Great Aunt Myrna's fingernails will be pulled out one by one by peace retreat guru, Krista, real name Stan Bogden, and sent to them in the post if they cannot find the missing Ark of the Coven. The message is for the twins because it is family legend that they will inherit special powers on their birthday on Friday 13th. Pixie and Angel think they are potty. They find out that the Ark of the Coven contains a 13th Century spell of enchantment. Pixie is desperate to cast the spell and make Jed fall in love with her. As the roller-coaster search continues, with time running out, they enter a world of witches, seances and ghostly sightings.