They had dug a tunnel.

“How long has this been here?” Walli asked. If his sister had known about it last year she might have escaped this way, and avoided Bernd’s crippling injury.

“Too long,” said Danni. “We finished it a week ago.”

“Oh.” That was too late to have been any use to Rebecca.

Danni added: “We only use it in twilight. In daytime we would be too visible, and at night we would have to use flashlights, which might call attention to us. All the same, the risk of discovery increases every time we bring people across.”

A young man in jeans came up a ladder out of the hole: presumably one of the student tunnelers. He looked hard at Walli, then said: “Who’s this, Danni?”

“I vouch for him, Becker,” said Danni. “I’ve known him since before the Wall went up.”

“Why is he here?” Becker was hostile and suspicious.

“To go across.”

“He wants to go to the East?”

Walli explained: “I escaped last week, but I need to go back for my girlfriend. I can’t cross by a regular checkpoint because I killed a border guard, so I’m wanted for murder.”

“You’re that guy?” Becker looked at him again. “Yeah, I recognize you from the photograph in the paper.” His attitude changed. “You can go, but you haven’t got much time.” He looked at his watch. “They’ll start coming through from the East in ten minutes exactly. There’s hardly room to pass someone in the tunnel, and I don’t want you to cause a traffic jam and slow down the escapers.”

Walli was scared, but he did not want to lose this chance. “I’ll go right away,” he said, concealing his fear.

“Okay, go.”

He shook Danni’s hand. “Thanks,” he said. “I’ll be back for my guitar.”

“Good luck with your girl.”

Walli scrambled down the ladder.

The shaft was three yards deep. At the bottom was the entrance to a tunnel about a yard square. It was neatly built, Walli saw immediately. There was a plank floor, and the roof was propped at intervals. He dropped to his hands and knees and began to crawl.

After a few seconds he realized there were no lights. He kept crawling as it became completely dark. He felt viscerally scared. He knew that the real danger would come when he emerged into East Germany at the other end of the tunnel, but his animal instincts told him to be frightened now, as he crawled forward unable to see an inch in front of his face.

To distract himself, he tried to picture the streetscape above. He was passing beneath the road, then the Wall, then the half-demolished houses on the Communist side; but he did not know how much farther the tunnel went, nor where it terminated.

He was breathing hard with the effort, his hands and knees were sore from crawling on planks, and the bullet wound in his calf was burning with pain; but all he could do was grit his teeth and go on.