Carol MacLaine is the younger sister of Thomas MacLaine. She owns and operates the Galaxy of Terror bar, mostly by herself, though she clearly has a piano player to accompany her when she sings and relies on her brother to make drinks and food.
For some unknown reason, she's very angry and hostile towards most members of Greenvale, especially Diane Ames. She may have been friends with Anna Graham and Becky Ames, but seems closest to her brother Thomas. She is very rude to Agent York and can hardly be bothered to answer his questions and tends to depart suddenly.
Later she and her brother Thomas are revealed as accomplices of George, The new Raincoat Killer