Who is Eileen Wade from The Long Goodbye and what is their importance?

Eileen Wade is Roger's wife. She is described as a beautiful woman, who looks over Marlowe while Spencer is seeking his services to watch Eileen's husband, Roger. When Marlowe refuses the job, Eileen goes to Marlowe's office and tells him that her husband is actually missing and that she is worried. In reality, she simply wanted Marlowe involved in the case because of his connection with Eileen's first husband, Terry Lennox. In the end, we learn that Eileen murdered both Sylvia and Roger Wade.