There is no problem that magic can't solve
While she was traveling in the Dessarin Valley Gandalf was captured by what she believed to be bandits at the time. They actually turned out to be cultists who were living at the Sacred Stone Monastery. Forced into slavery and with her spell book confiscated Gandalf toiled away in the mines for many weeks.
However she was rescued by a group of heroes who aided in recovering her spell book. As thanks Gandalf agreed to accompany them for a time until they could reach civilization.
Last known Gandalf was in Red Larch resting up from her ordeal.