Meet Merricat. She's eighteen, and lives with her uncle, who cannot leave the house, and her sister, who does not. The rest of her family is dead. Twice a week she leaves the house to go to town for groceries. The townspeople talk about her behind her back, and sometimes to her face. She's not allowed to handle knives, prepare food, or pick mushrooms.
Merricat also has her rituals and her private magic. She buries knick knacks around the property, for protection, for cursing, or to encourage growth. She nails items to trees, also for protection. She thinks of words which, if left unspoken, will keep all in her family safe.
Merricat loses her temper easily. She smashes glasses and water jugs when her ordered, ordinary life is disrupted. She loves her sister, and wants to protect her from anyone who would pry, anyone who would ask her questions about the day the rest of their family died. Her uncle Julian thinks of little else. So Merricat begins her rituals again, and her private magic.
And then their cousin Charles comes to visit. And the careful, structured routine of their lives behind to break.