A Hat Full of Sky

First published on 6 May 2004 by Doubleday. It is the thirty-second Discworld novel and the second Tiffany Aching book.

A hiver is an ancient creature — very old, made of many fragments of stolen minds — that possesses a living host and uses them until they burn out. It is drawn to people of power and ambition, which makes young Tiffany a target.

Granny Weatherwax becomes Tiffany's primary mentor in this novel, establishing the relationship that defines the rest of the Tiffany Aching books. Granny's philosophy — 'headology', the power of personality, and the idea that witchcraft is mainly about taking responsibility — shapes Tiffany's entire development.

The title is a Scottish expression meaning a head full of ideas or plans — 'a hat full of sky' suggests ambition beyond what one can currently hold. It speaks to Tiffany's tendency to take on more than she can safely manage.

Yes, though it is written for younger readers. The themes — identity, what it means to be yourself, the cost of ambition — are handled with the depth that characterises the best children's fantasy.