Todhunter Moon, Book One: Pathfinder: 1 (Septimus Heap: Todhunter Moon)

Tod has grown up a PathFinder, one of an ancient seafaring tribe. Her mother, who died when Tod was young, had a very different history. She was from a mysterious magykal desert-dwelling family. When Tod's father disappears she is not only alone, but soon finds herself swept into the path of an evil sorcerer. Now Tod must choose which of her pasts will help her to survive: PathFinder or Magician.