[1] A full colour supplement to the series, entitled The Magykal Papers, was published in June 2009, and an online novella titled The Darke Toad is also available.

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.

Sage described Septimus Heap's world as a place where numerous creatures and people suddenly appear and become involved in events.

[4] Commenting on the development of the Septimus Heap character, Sage has described him as someone in a strange and hostile world who has no idea of his real identity.

[8] The plot of the first book, entitled Magyk (published in March 2005), revolves around the pauper Heap family: Silas, Sarah and their seven children.

Septimus is born on the same day, but is declared dead by the midwife, who steals the baby and brings him to DomDaniel, an evil wizard.

They are accompanied by a member of the Young Army called Boy 412, who discovers his magic powers and a legendary ring while at Zelda's.

The second book, Flyte (published in March 2006), begins with Septimus (now the apprentice to ExtraOrdinary Wizard Marcia Overstrand) witnessing the kidnapping of Jenna by her older brother Simon Heap.

The antagonist of the third book, Physik (published in March 2007), is the 500-year-old spirit of Queen Etheldredda, who is accidentally released by Silas Heap.

In the present timeline of the novel, the Castle is infected by a deadly plague created by a rat like creature owned by Queen Etheldredda who has the plan to acquire eternal life.

Marcia then destroys the substantial spirit of Etheldredda and Septimus brews an antidote to the plague (Sicknesse) using his knowledge of Physik.

When they reach the house, Septimus meets Hotep-Ra, the first ExtraOrdinary Wizard, while Jenna and Beetle find Nicko and Snorri.

Beetle becomes Chief Hermetic Scribe; Simon is reunited with his family after leaving his past behind and Princess Jenna is happy that the Palace and Castle are back to normal.

Fyre (published in April 2013), sees the cast featuring the toughest challenges yet as Septimus nears the end of his ExtraOrdinary Wizard training.

Septimus Heap: The Magykal Papers (published in June 2009) is a supplement to the series in a full-colour larger format with illustrations by Mark Zug.

[10] It was announced on 17 July 2009 that the movie would be live action, with computer-animated effects, and David Frankel as director and Rob Lieber to adapt Magyk.

[15] As of 2009, a re-write of the script was being done with screenwriter Mulroney while Warner Brothers were working with a studio to create some early conceptual design/look development.

For most of the first novel he appears as Boy 412, a child from the Young Army, where he has spent the first ten years of his life after DomDaniel attempted to abduct him.

According to a review in the Manila Standard Today, the contrast between the caution he has learned from an early age and his longing for the love and affection of a family makes him an intriguing character.

The ambiguity of Jenna's characterization has been questioned, with one critic commenting: "[A]s the Princess or Queenling, she comes from a turbulent past and is thrust into the anonymous world of ordinary society without any inkling of her royal background.

The book ends with a quote from Arthur C. Clarke: "Any Sufficiently Advanced Technology is Indistinguishable from Magyk," hinting that the series is set in the far future.

Hints that the story is set in the future also reveal themselves when Septimus and the possessed Syrah enter a chamber that goes up and down with the press of a button, indicating that they used an elevator.

Built by the first ExtraOrdinary Wizard, Hotep-Ra, it is a marble 21-floor tower with a gold pyramid at the top, surrounded by an aura of magyk.

To the south of the Castle are the Marram Marshes, a long stretch of marshland near the mouth of the river, which is inhabited by many creatures, such as Brownies, Quake Oozes, Boggarts and pythons.

The Forest has many mysterious aspects, and is dominated by shape-shifting or carnivorous trees, including Benjamin Heap, wolverines, and secrets.

"[5] The Badlands are a rocky and hilly valley on the northern borders of the Septimus Heap world, where Dom Daniel once practised his dark magic in an observatory atop a hill.

They are inhabited by Land Wurms, giant carnivorous snakelike animals, making them a dangerous place, where Simon Heap also used to live.

The Septimus Heap novels have been published in 28 languages worldwide and have sold over one million copies in the United States, with each of the books appearing on national bestsellers lists.

[25] Published in March 2005, the first book, Magyk, became an international bestseller after it appeared at number one on the New York Times Best Sellers List.