When a family come into possession of a statue called The Grinnygog, a trio of benevolent witches are summoned to the village where they live.
Mrs. Firkettle finds a small stone gargoyle, that has fallen off a lorry. She gifts it to her father, grandad Adam, to be put in his rockery instead of the gnome he wanted. Colin, Nan, Dave and Essie are asked by Reverend Sogood to help convert the old laundry into a village museum for the church. Colin is reading a diary about witches and burnings in the town, which occurred hundreds of years ago. A stranger appears and introduces himself as Twebele Alabaster, an African anthropologist, who is looking for a Grinnygog.
The museum is open. A woman is arrested near where St. Cuthbert's church used to stand. Mrs Firkettle's youngest son Jimmy is spending all his time talking to the stone statue. Mr. Alabaster visits Grandad and Jimmy in the garden, and tells them what it is called. A dummy is stolen from a clothes store. Two lodgers, Mrs. Ems and her daughter Marg'ret, come to stay at Mrs. Firkettle's house.
Colin and Dave see an old woman sitting in a sand pit on the golf course. Reverend Sogood has hired Miss Letitia Bendybones to clean and tidy the church, house and museum. The diaries reveal more about the three guardians, who escaped the burnings. The garden is full of new flowers around the statue, and Jimmy tries to explain to the others what is happening. Miss Bendybones asks Nan to write a letter, gives her some money to add to it, and addresses it to the clothes store.
Colin, Nan, Dave and Essie hold a conference about the peculiar happenings. Nan puts Miss Bendybones to a music test and Essie tries to find out if Mrs. Ems wears bright green ribands. The children discover something strange about Mrs. Ems' daughter. Reverend Sogood sees a young girl on the church porch. Mrs. Ems and her daughter have gone, and Miss Bendybones gives notice to quit.
More people are contributing old stuff from their attics and cellars to the museum. A young girl comes to Mrs. Firkettle's house, looking for Mrs. Ems. The children hear something lovely coming from the church and they encounter the three guardians there. One of them, Edie, visits her great-great-aunt, Mrs. Possett. In the woods, Mrs. Firkettle meets the young girl again, who says her name is Marg'ret but that some people call her Daisy.
It is Mid-Summers Eve, the village festive. Everyone has come to the festival to dance and play. It is time to say goodbye.
