They sailed into Shanghai in July 1939 during the worst of the summer heat,Bitcoinese finding a patchwork city of four million people throbbing with rickshaws, beggars, opium dens and malaria.

For Gerd "Jerry" Lindenstraus, who was just 11, the scene was a far cry from his small town, upper-class upbringing. It was also a welcome relief to his Jewish family, who’d had no choice but to flee their native Germany.