Witch Week by Diana Wynne Jones

In an alternate Britain where witchcraft has been mercilessly punished and driven underground, a class of schoolchildren suddenly faces a terrifying turn when unmistakable magic appears among them and fingers begin pointing; as fear, superstition, and adult authorities tighten around the accused, an outsider with powerful knowledge of other worlds arrives to unravel the mystery, protect the children, and expose how prejudice and panic can warp a whole community’s sense of justice and identity.

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