Mr. and Mrs. Cuthbertson-Jones are surprised when their expected baby turns out to be twin girls and distressed when they find that one of them is perfectly good and the other perfectly evil.
Although thirteen-year-old Willa Jo and her Aunt Patty seem to be constantly at odds, staying with her and Uncle Hob helps Willa Jo and her younger sister come to terms with the death of their family's baby.
Only twelve-year-old Colleen knows that her baby sister died just after she was born and that Colleen put another baby in her place, until the baby's father shows up and makes trouble for her and her family on the South Dakota prairie in the 1860s.
Rosa is excited when her new cousin, Benji, is born, but when Grandma wants to remove a beloved armchair, Rosa puts her foot down and insists that the chair, just like Benji, is a member of the family.