Subway Music is about finding things Reinhold Junker thought he had lost forever: his subway music and his name.
Subway Music begins in a Manhattan hotel room the day after he and his wife celebrated their Christmas anniversary. She coaxes him into taking her to Brooklyn to see where "all those stories you tell all of the time about growing up" took place. As a certified Californian, that's the last thing he wants to do. Subways were then. Freeways are now. But they go.
At Prospect Park he "finds" his father and learns about both courage and reverse prejudice-prejudice against his "Nazi" father. At Coney Island he remembers his Jewish best friend and futile attempts to convert him to Catholicism using the holy waters of Coney Island to turn him into a Jewish Cary Grant. At Kings Highway he visits the house haunted by his old ghosts.
At the end of Subway Music he realizes that subway music and Brooklyn will always be as much a part of him as the color of his eyes or the color of his hair. Being from Brooklyn was his fate. Being a Californian is just the way things sometimes work out.