When Hannah steals her grumpy grandfather's glass eye, she is transported into the Green World, a forest fairy world where Queen Tatiana and King Oberon are locked in a deadly feud, resulting in problems that will destroy both fairyland and the human world.

Hannah manages to escape, but recruits her best friend, Meg, to go back, hoping the two of them together can fix everything. Before the girls can do more than talk with the queen, the king kidnaps Meg!

With Tatiana's help, Hannah must find, and then bargain with the king to get Meg back. Between trips into the Green World and scary visits to her human grandfather, Hannah discovers she has the power to stop the war and restore the thrones to the fairy king and queen. Hannah keeps the glass eye, with the blessings of the king and queen, so she can always travel back to the Green World.