She had come to see the band but they were away. Well, Jim A. was *permanently* away, replaced by this mysterious Jim B. who was 20 years younger. And what about herself? Also 20 years displaced. It was 20 years ago today (etc.).
The Band; a make-believe one inside a real one. But the make-believe one had come to overshadow the real, like a Virtual Reality within Reality Reality begins to take over and work its powers outside in as well as inside out. Glove.