“I knew it!” I gave Darcy an excited smile.

“He’s a small-time gangster called Mickey ‘the Weasel’ McHenry. Small potatoes, as I said. On the fringes of big crime. Acts as driver, lookout, that kind of thing. Has done time for receiving stolen goods, participating in a robbery.”

“So a criminal element is involved in this,” Darcy said.

“Almost certainly. So the question is still, who was the dead man, and who wanted to kill him?”

“As I mentioned before, the only suspicious person who was seen near the castle recently is the one who called himself Professor Peabody,” Darcy said. “We checked with Trinity College and he was not known there. And we have a better description of him now: about six foot two, not fat but stocky, large head, sagging jowls and a bulldog look to him.”

Lennox was actually smiling. “I knew it! That’s a good description of Lofty Schultz,” he said.

We looked at him expectantly.

“Lofty Schultz, member of the Lake Shore Gang. They had been a powerful force in Chicago crime since the twenties. Made their first money in bootlegging rackets. Then, when liquor was made legal again, they set their sights on bigger things.” He paused, taking a deep breath. “In 1929, before the crash, they pulled off the heist of a US mail truck containing cash, bonds and jewelry. Two million dollars’ worth of assets.”

Darcy whistled.

“Which was never recovered,” Lennox went on. “They took off in a getaway van, leaving Lofty Schultz behind. He was arrested. There wasn’t enough evidence to pin that crime on him and he was sent to Leavenworth federal prison in Kansas for five years on a lesser charge of tax evasion. He was released after four years for good behavior.”

“So what happened to the money and the rest of the gang?” Zou Zou asked. She had seemed composed at first, but now she was sitting on the edge of her seat.

“The gang split up. We think Weasel McHenry was the driver but again it was never proved. We think the gang leader’s girlfriend, Lola Martinez, was the one who made sweet with a contact at the US post office and got the information on when the shipment was going to be sent. Neither of them was caught or prosecuted and both seemed to have vanished off the face of the earth. However, two of the big players were caught. Skeets Kelly—we reckon he pulled the trigger that shot the mail truck driver—and Bugsy Barker. Bugsy was the gang leader. He masterminded the whole thing. They were both sentenced to life and later moved to the federal prison on Alcatraz. That’s an island prison in San Francisco Bay. No one has ever escaped from it. The freezing water and the currents make swimming impossible for more than a few minutes.”

“So they are still there?” I asked.