On New Year’s Day in 1988, Abdullah Ali, an Iraqi businessman who had been living in London for eight years, joined three compatriots for dinner at a restaurant called Cleopatra in Notting Hill.The next morning, he was taken ill with flu-like symptoms and was admitted to hospital. There his condition rapidly deteriorated — his hair fell out, he developed excruciating skin and joint pain, and paralysis and respiratory failure began to set in. Fifteen days later he was dead — but not before he had begun to wonder whether something had been added to his vodka. He was right: the...