This one is really just an Honorable Mention, but I’m featuring it because of how influential this series was to me when I was younger – I rediscovered it at the library recently, and realized it was, generally speaking, a Girls Underground story too!
Witch’s Sister is the first of three witch books by Phyllis Reynolds Naylor, written in the 70’s. Lynn believes her sister Judith is being turned into a witch by their mysterious old neighbor Mrs. Tuggle. She and her friend Mouse spy on Judith and see all manner of strange happenings, and Mouse begins reading an old book on witchcraft, and matching up the legends with Judith’s actions. It appears that the witches are specifically after Lynn’s baby brother, so like a typical GU she must rescue him. The climax of this particular book happens during a stormy night when Lynn’s parents have gone away, and she is left with the witches to defend her brother. She confronts them alone, and manages to foil their plans. But, things are obviously not over, and the story continues in the following books.
This book features the creepy little cantrip that I loved so much I memorized it, and still use it to this day:
From the shadows of the pool,
Black as midnight, thick as gruel,
Come, my nymphs, and you shall be
Silent images of me.
Suck the honey from my lips,
Dance upon my fingertips,
When the darkness tolls the hour,
I shall have you in my power.
Fast upon us, spirits all,
Listen for our whispered call.
Whistling kettle, tinkling bell,
Weave your web and spin your spell.