He noticed the song playing over the sound system.

Except that he didn’t just notice it. He recognized it. Recognized that it was called “Me and You and a Dog Named Boo” and that it concerned a young man who traveled across the country in an old car, without any destination in mind. Henry tried to tell himself that he must have noticed the song in his teens because its philosophy of aimless wandering annoyed him so much, but that didn’t explain why he had just caught himself humming the tune. And it didn’t explain why his foot was tapping under his shopping cart, or why he suddenly knew that the song’s singer would end up in Los Angeles only to feel that restless urge to hit the road again.

Even though the minutes were counting down until his manager’s special steak would expire, Henry stayed in the aisle until the song ended and the next one began. To his shock, he realized he knew this song, too. Even though the lyrics made no logical sense, Henry was now aware that he’d long felt great sympathy for a balloon seller named Levon whose only sin was the sincere desire to be a good man.

This was an astonishing discovery for Henry, and he prowled the aisles for an hour, filling his cart with enough groceries to keep him through Christmas as he allowed the sound system to ferry song after song from the depths of his subconscious to the front of his brain.

That shopping trip sent Henry on a six-month odyssey through the annals of pop history. He worked thoroughly and methodically, just as he had when he was investigating murders for the Santa Barbara Police Department. He started by Googling pop charts for the years he was in high school-years, his half hour of scientific research assured him, when pop music has its greatest impact on the human mind-and then plugged those titles into the search box of the iTunes store, playing the free thirty-second sample of each song.