What is the theme in Witch Child by Celia Rees?

Witchcraft, of course, is a major theme: it drives the action of the novel. The novel begins with Mary announcing she is a witch. She describes how her grandmother, Eliza Nuttall, was tried as a witch and hanged. Their neighbors whisper that Mary may have the same powers as Eliza, so a stranger who turns out to be Mary's long-lost mother rescues Mary and takes her to an inn where she is dressed as a Puritan and learns that she will be sent to America for safety.