There are, in the universe, an infinite number of worlds, each split off from its neighbors by the turnings of history. In one world, very much like ours, witchcraft is illegal and witches are burned, unless they can manage to escape. A large number of witch-orphans have been sent to Larwood House, a government-run boarding school. A note accusing someone at the school of being a witch is only the beginning of the strange occurrences.

Young Charles Morgan has just discovered that he can cast spells. Nirupam Singh's brother was burned as a witch. Nan Pilgrim has just taken her first flight on a broom. Among the other students at the school are Estelle Green, whose mother used to run part of the witches rescue service; Brian Wentworth, whose father is assistant head and who has begun acting decidedly odd; and the perfect Simon Silverson, whose every word suddenly starts coming true.

When one of the students disappears and a note is left blaming the witch, everyone begins to get scared and several students run away. Nan and Estelle, trying to reach the witches rescue service, are given a spell that will summon help, in the form of the wizard Chrestomanci.

Witch Week is part of Diana Wynne Jones's Chrestomanci Quartet, which also contains Charmed Life, The Magicians of Caprona and The Lives of Christopher Chant. No knowledge of the rest of the series is necessary in order to enjoy this novel.

The book is well-paced, and the two main characters, Charles and Nan, are engaging. The story is told from the point of view of many of the students and even a couple of the teachers at Larwood House. This may leave the reader feeling a bit muddled, as there is often more than one viewpoint character on stage. Much of the story hinges on the historical figure of Guy Fawkes, which might mystify American readers, although an editor's note (which I missed when I initially started reading) is included at the beginning of the book briefly summarizing his importance. Despite these small flaws, the book is quite enjoyable.

Fans of Harry Potter -- bet you were wondering how I'd work him in -- will enjoy this older work and will most likely want to search out the other books in this series.