The series follows the adventures of Septimus Heap who, as a seventh son of a seventh son, has extraordinary magical powers.
After he becomes an apprentice to the (“ExtraOrdinary”) wizard of the series, Marcia Overstrand, he must study for seven years and a day until his apprenticeship ends. In the first book, he is known as Young Army Expendable Boy 412, until his great-aunt, Zelda Zanuba Heap reveals his true identity.
His adventures are placed in the context of the warmth and strength of his family, and developed alongside those of Jenna, his adoptive sister, who is heir to the throne of the Castle, the community where they live. The novels, set in an elaborate fantastic world, describe the many challenges that Septimus and his friends must overcome.