Jenna Heap is a leading character in the Septimus Heap book series by Angie Sage. She is the adoptive sister of Septimus and the adoptive daughter of Silas and Sarah Heap. Jenna has many friends in the book, and many enemies, too. Although she acknowledges they are not her birth family Jenna loves her adoptive familym including her seven brothers, her grandfather Benji, her parents, and her Aunt Zelda.

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.