The falling woman.

Elizabeth Waters is an archeologist who can see 'shadows' of the past, something she keeps a secret and that's both a blessing in that it points her towards archeological discoveries, and a curse that has her sometimes doubting her sanity. On an archeological dig in an ancient Maya site in the Yucatan, the 'ghost' of an Maya priestess communicates with Elizabeth. When Elizabeth's estranged daughter arrives on the scene, both are pulled into the supernatural world of ancient Maya magic. 1988 Nebula Award winning novel.