Pre-Owned The Timekeeper's Moon (Hardcover) by Joni Sensel

When Ariel Farwalker hears the moon talking to her, she thinks she must be going crazy. Then she discovers an ancient map, and learns that the moon is part of a mysterious summons that's calling her on a new journey.

With her surly guardian Scarl by her side, Ariel sets out on an adventure that leads her to new friends-the beautiful Flame-Mage Sienna and the mute boy Nace, who captures Ariel's heart. As the four travel on, strange things start to happen-fragments of Ariel's past appear in the present, so that it seems that time itself is coming undone. At the end of the journey, Ariel will learn where her journey began, and have a chance to save her life as she knows it.