Laurel is clearly the antagonist in this novel, although she's not exactly an enemy -- she's more like a completely self-interested individual doing what she has to do to save her own life or pursue her own interests, without heat. When we first meet Laurel, it is at the funeral of Mrs. Mabel Tatiana Leroy Perry, where most of the items and assets mentioned in the will seem to be going to her daughter, Mrs. Eudora Mabel Lorelei Perry Lynn. Or, Laurel.
The first thing that is an issue for Polly Whittacker is that Laurel is the ex-wife of Thomas Lynn. He tells her so himself, when they first meet and talk during the funeral. Polly meets Laurel as she and Tom are looking through the pictures he has been allowed to choose from. In this, Polly recognizes Laurel as the person she had mistaken at first for her friend Nina when Polly had tried to follow her friend, but ended up crashing the funeral without knowing she was doing so.
Laurel had light-colored hair, which might have been gray, or might have been no color at all. It seemed to float around her head. She also gave off a powerful aura of sweetness, although Polly could tell, once she'd looked into Laurel's strange, light-colored eyes with black rings in the lightness, that Laurel had no more feeling than the tunnel her eyes seemed to pull you into. Laurel, in short, was frightening.