Ron Carlson’s latest novel, “Return to Oakpine,” is a tender and nostalgic portrait of western American life. In it, Carlson tells the story of four middle-aged friends who once played in a band while growing up together in small-town Wyoming. One of them, Jimmy Brand, left for New York City and became an admired novelist. Thirty years later in 1999, he’s returned to die. Craig Ralston and Frank Gunderson never left Oakpine; Mason Kirby, a Denver lawyer, is back on family business. Jimmy’s arrival sends the other men’s dreams and expectations, realized and deferred, whirling to the surface. And now that they are reunited, getting the band back together might be the most essential thing they ever do.