Based on the novella Witch by Rebecca Little.

The precocious and fiercely independent Aima tells her babysitter that the Witch they created in a game of make-believe will never stop chasing them. While the babysitter initially tries to deny Aima’s insistence that the Witch is evil, soon they follow Aima into a world where imagination rules and wildness, magic, and delight are hidden around every corner. Their adventures bring them together with fairies, ghosts, star-lovers, and UFOs, and as they march toward their showdown with the Witch, the unreal becomes reality and the lines between good and evil are blurred. As Aima and her babysitter draw closer and closer to facing down the Witch and the source of her powers, the babysitter must come to terms with what they lost and gained by growing up and learns that sometimes we have to let go to return.