Possession

Possession is the eighth book in the Daughters of the Moon series. It was first published in the United States on September 1, 2002. This book focuses on Serena Killingsworth.

Official Summary
"Serena hasn't been herself lately. She's been having sudden lapses of memory and finds herself acting like a completely different person - one she doesn't like very much. To add to her confusion, she knows that someone has been following her. It all started the night an elderly woman helped her. Now Serena is beginning to wonder: Who was that woman? And what has she done to Serena?"