The replacement (Mildred x Ethel)

A new witch arrives at Cackle's: Sadie Harroway, a girl from Mildred's childhood, carrying old grudges and sharper magic than anyone expected. Overnight, Mildred goes from having one enemy to two.

Ethel Hallow, long used to being Mildred's only rival, spirals as Sadie slips effortlessly into the role she once held. Jealousy twists into obsession, Sadie's cruelty grows darker. Mildred begins to feel like the universe itself is targeting her, Ethel can't understand why she cares so much, and Sadie seems determined to tear everything apart.

By the end of the year, secrets, feelings, and past mistakes threaten to surface, and nothing between them will ever be the same.