Karolin was doubtful about the lyrics, which mentioned justice and freedom.

Walli said: “In America, Pete Seeger is called a Communist for writing it! I think it annoys bullies everywhere.”

“How does that help us?” Karolin said with remorseless practicality.

“No one here will understand the English words.”

“All right,” she said, giving in reluctantly. Then she said: “I have to stop doing this, anyway.”

Walli was shocked. “What do you mean?”

She looked somber. She had saved some piece of bad news so that it would not spoil the sex, Walli realized. Karolin had impressive self-control. She said: “My father has been questioned by the Stasi.”

Karolin’s father was a supervisor at a bus station. He seemed uninterested in politics, and was an unlikely suspect for the secret police. “Why?” said Walli. “What did they question him about?”

“You,” she said.

“Oh, shit.”

“They told him you were ideologically unreliable.”

“What was the name of the man who interrogated him? Was it Hans Hoffmann?”

“I don’t know.”

“I bet it was.” If Hans was not the actual interviewer, he was surely responsible, Walli thought.

“They said Dad would lose his job if I continued to be seen in public singing with you.”

“Do you have to do what your parents say? You’re nineteen.”

“I’m still living with them, though.” Karolin had left school but was at a technical college studying to be a bookkeeper. “Anyway, I can’t be responsible for my father getting the sack.”

Walli was devastated. This blighted his dream. “But . . . we’re so good! People love us!”

“I know. I’m so sorry.”

“How do the Stasi even know about your singing?”

“Do you remember the man in the cap who followed us the night we met? I see him occasionally.”

“Do you think he follows me all the time?”

“Not all the time,” she said in a lowered voice. People always spoke quietly when mentioning the Stasi, even if there was no one to overhear. “Maybe just now and again. But I suppose that sooner or later he noticed me with you, and started tailing me, and found out my name and address, and that’s how they got to my father.”

Walli refused to accept what was happening. “We’ll go to the West,” he said.

Karolin looked agonized. “Oh, God, I wish we could.”

“People escape all the time.”

Walli and Karolin had talked of this often. Escapers swam canals, obtained false papers, hid themselves in truckloads of produce, or just sprinted across. Sometimes their stories were told on West German radio stations; more often there were all kinds of rumors.

Karolin said: “People die all the time, too.”

At the same time as Walli was eager to leave, he was tortured by the possibility that Karolin would be hurt, or worse, in the escape. The border guards shot to kill. And the Wall changed constantly, becoming more and more formidable. Originally it had been a barbed-wire fence. Now in many places it was a double barrier of concrete slabs with a broad floodlit middle patrolled by dogs and guarded by watchtowers. It even had tank traps. No one had ever tried to cross in a tank, though border guards fled frequently.