Our narrator tells us that he's actually had some personal experience with witches, all before the age of eight.
One of these encounters ended badly, and the only reason he's around to tell the frightening tale is because of his grandma. Thanks, grams.
Now we get a little back-story on our narrator and his family: his grandma is Norwegian (Grandma means "awesome" in Norway. Not really, but it might as well.). He was born in England, where his father worked, but he loved spending time in Norway with his grandma because they had a pretty special thing going on.
Sadly, his parents died in a car accident. He was in the car, too, but survived with just a cut. He doesn't like to talk about it.
Narrator and grandma decided they'd stay in Norway, because grandma loved that place more than anything in the world.
As grandmas do, our narrator's loved to tell stories. His favorites were the tales about witches, because, according to grams, they were all true, flat out true. Unfortunately, that meant that – since witches were still around – history could repeat itself.
The narrator was a little skeptical. He's didn't quite believe in witches.
Now that we have the history, the story begins:
Our narrator is about seven years old. As he sits on the floor next to his grandmother's armchair, she tells him to listen carefully to her warnings about witches. All he can do after that is just pray for the best. Hmmm, that's not very reassuring.
He's still a little skeptical. (So are we.)
Grandmamma tells him that she knows five children who vanished because of witches. She smokes a cigar, and starts to tell the story of each child. We'll list them in a row, but keep in mind that our curious little narrator asks about a zillion questions along the way. Grandma is patient with him – although at one point she offers him a puff of her cigar, so maybe she's trying to drug him so he'll keep quiet.
Ranghild Hansen. A tall woman with gloves lured her away, and she was never seen again.
Solveg Christiansen. A lady gave her an apple and, the next day, she appeared in a painting in her family's house. That's right, she was in the painting – she'd move from place to place, and age over time, and eventually she disappeared altogether.
Birgit Svenson (oh, Norwegian names). She turned into a chicken and laid eggs. (At this point, the narrator calls Grandmamma out on having said that all these children had vanished – turning into a chicken is not vanishing. Grandma blames her mistake on old age.)
Harald (Roald Dahl's father's name, BTW). He turned into a stone. Now he's used as an umbrella holder, end of story.
Leif. One day, he was swimming. When he came up for air, he was no longer a boy, but a porpoise. He played with his family for a while – he still had the voice of Leif, that's how they knew it was him – but then he swam away and was never seen again.
In Norway, Grandmamma says, these happenings are almost expected. They're commonplace.
This scares our narrator, who worries that he might get stolen from his bedroom at night, but his grandma reassures him that that's not how witches operate. Sweet dreams, dear narrator...