Physik is a fantasy novel by Angie Sage. It is the third book in the seven-book Septimus Heap series. The story focuses primarily on the 500-year-old spirit of Queen Etheldredda, who attempts to use Septimus Heap to attain immortality.

Flyte is a 2006 children's novel by Angie Sage and the second book in the Septimus Heap series. The book's cover was modelled after the in-story book: How to Survive Dragon Fostering: A Practykal Guide with the Flyte Charm lying on top. Flyte was released in March 2006 through HarperCollins and Bloomsbury Publishing.