Gwen is a woman that Jerry met at Tim Whatley's Hanukkah party. Jerry goes out with Gwen a few days later, but when she arrives Jerry finds that she is completely unattractive. Jerry later describes the situation to George and he explains that Gwen is a "two-face": someone who looks pretty in one instance and ugly in another.
Jerry meets Gwen in a taxi later and is relieved to see that she is pretty once again. As they try to decide where to eat, Gwen's face changes back and forth between pretty and ugly, to Jerry's confusion. Jerry learns that the only place where Gwen always looks good is in a back booth at Monk's; Jerry decides to only see Gwen at Monk's, because he really likes the coffee shop. Gwen is annoyed, however, that they only go to the coffee shop. Upon finding a rubber band in her soup, Gwen leaves.
Gwen runs into Kramer outside of H&H Bagels. Since Kramer has only seen her with her "ugly" face, he does not recognize her. She explains that she is dating Jerry, but Kramer corrects her and tells her that she is much prettier, and a foot taller. Gwen comes to the conclusion that Jerry must be seeing someone else, and that's the reason why he only wants to see her at Monk's, so that he doesn't get caught.
Gwen shows up at the Festivus dinner at the Costanzas' place to confront Jerry. She believes Elaine is the "ugly girl" that Jerry has been seeing, and storms out. Jerry rushes to explain, but quickly turns away when he sees Gwen in bad lighting on the front porch.
* Beverly Hills, 90210