Ever since Kaye’s grandfather died, she’s been obsessed with counting things: the steps to her bedroom, the dolls on her sister’s bed, even the threads on her favorite blanket. It’s arithmomania, and with the selective mutism that sometimes prevents her from speaking, she literally can’t find the words to talk about how she feels now that Grampa is gone.

When Kaye and her younger sister Holly encounter a strange man who calls himself the Poppet Maker, Holly wins an exquisite doll that looks just like her. Kaye feels sure something is wrong, and soon Holly-doll guides her sister to discover an ever-increasing number of creepy dolls.