Back inside, a blond girl was strumming a guitar and singing “Freight Train.” She was not as beautiful as Karolin, but she was pretty in a more obvious way. Next, a virtuoso guitarist played a complicated fingerpicking blues. Then Danni Hausmann called Walli’s name.

He felt tense as he faced the audience. Most of the guitarists had fancy leather straps, but Walli had never bothered to get one, and his instrument was held around his neck by a piece of string. Now, suddenly, he wished he had a strap.

Karolin said: “Good evening, we’re the Bobbsey Twins.”

Walli played a chord and began to sing, and found he no longer cared about a strap. The song was a waltz, and he strummed it jauntily. Karolin pretended to be a wanton strumpet, and Walli responded by becoming a stiff Prussian lieutenant.

The audience laughed.

Something happened to Walli then. There were only a hundred or so people in the place, and the sound they made was no more than an appreciative collective chuckle, but it gave him a feeling that he had not experienced before, a feeling a bit like the kick from the first puff of a cigarette.

They laughed several more times, and at the end of the song they applauded loudly.

Walli liked that even better.

“They love us!” Karolin said in an excited whisper.

Walli began to play “Nobody’s Fault but Mine,” plucking the steel strings with his fingernails to sharpen the drama of the plangent sevenths, and the crowd went quiet. Karolin changed and became a fallen woman in despair. Walli watched the audience. No one was talking. One woman had tears in her eyes, and he wondered if she had lived through what Karolin was singing about.

Their hushed concentration was even better than the laughter.

At the end they cheered and called for more.

The rule was two numbers each, so Walli and Karolin came down off the stage, ignoring the cries for an encore, but Hausmann told them to go back. They had not rehearsed a third song, and they looked at one another in panic. Then Walli said: “Do you know ‘This Land Is Your Land’?” and Karolin nodded.

The audience joined in, which made Karolin sing louder, and Walli was surprised by the power of her voice. He sang a high harmony, and their two voices soared above the sound of the crowd.

When finally they left the stage he felt exhilarated. Karolin’s eyes were shining. “We were really good!” she said. “You’re better than my brother.”

Walli said: “Have you got any cigarettes?”

They sat through another hour of the contest, smoking. “I think we were the best,” Walli said.

Karolin was more cautious. “They liked the blond girl who sang ‘Freight Train,’” she said.

At last the result was announced.

The Bobbsey Twins came second.

The winner was the Joan Baez look-alike.

Walli was angry. “She could hardly play!” he said.

Karolin was more philosophical. “People love Joan Baez.”