First in Mary Janice Davidson's FBI agent trilogy.
I love that woman. She writes nothing that I would expect to enjoy, but I love every one of her books.
On the face of it- ridiculous. An FBI agent with Multiple Personalities? Who works with other agents who are sanity impaired?
But the story line carries through (mostly by sheer charm, I think) and I instantly went to the library catalog and put a hold on the next two as well.