The Witches by Roald Dahl

This is the story of Bruno, a young orphan. In 1967, he came to live with his adorable grandmother in the small rural town in England. While the little boy and his grandmother cross paths with witches as seductive as they are fearsome, the grandmother takes our budding hero to a sumptuous seaside resort. Unfortunately, they arrive just as the Chief Witch is gathering her henchmen from all over the world.