Septimus Heap, the seventh son of the seventh son, disappears the night he is born, pronounced dead by the midwife. That same night, the baby's father, Silas Heap, comes across an abandoned child in the snow -- a newborn girl with violet eyes. The Heaps take her into their home, name her Jenna, and raise her as their own. But who is this mysterious baby girl, and what really happened to their beloved son Septimus?