Who is Allison Manning from Dead in the Water: A Novel and what is their importance?

Allison Manning is accused of murderering her husband while on a yachting vacation. She is arrested and charged with his murder, and as a witness to her arrest, Stone Barrington quickly offers to become her defense attorney. Over the course of the novel, the reader comes to doubt Allison's story of what happened to her husband and assumes she is guilty. Stone, however, blinded by their affair fails to see the holes in her story.