In December 2016, a US official in Havana went to the embassy medical centre to report a debilitating and confounding illness. The symptoms included headaches; nausea; hearing loss; problems with memory and vision – and its onset was characterized by hearing… something. A buzzing, hissing, grinding… sound. Soon, a second official came down with the same symptoms. Then a third. Then a fourth. By the time the story went public in summer 2017, dozens of US diplomats, as well as some Canadians, had come down with what was becoming known as “Havana Syndrome.” In this deep dive investigation,...