Lynn's growing conviction that her sister is learning witchcraft from a neighbor reaches its peak when Lynn, her sister, and brother are left for a weekend in the neighbor's charge.

As more people fall under Mrs. Tuggle's spells, Lynn and Mouse grow more desperate in their efforts to find a way to stop the old woman's evil.

A series of mysterious events and the strange behavior of a group of their schoolmates convince Lynn and her best friend, Mouse, that the destructive power of a witch recently killed in a fire is still very much alive.