The 7th son of the 7th son, aptly named Septimus Heap, is stolen the night he is born by a midwife who pronounces him dead. That same night, the baby's father, Silas Heap, comes across a bundle in the snow containing a newborn girl with violet eyes. The Heaps take this helpless newborn 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?