The unrest in Meridian is growing and Prince Phobos is very pleased. His new plan is to have the underworld of Metamoor travel through a portal to Heatherfield. When Hay Lin's map alerts her that a portal is open, Will is the first Guardian to react. She travels through the strange royal gardens in Metamoor where she discovers Prince Phobos' dark secrets. Now Will needs the strength of all her friends to find her way out of the darkness.