In John Buchan’s last book, Sick Heart River, published posthumously in 1941, the protagonist, Sir Edward Leithen, has been given a year to live by an eminent London specialist, Acton Croke. A gas attack in the first world war has awakened tuberculosis as a delayed effect, and it is now galloping through his lungs. Although occurring only a handful of years before the discovery of streptomycin, Sir Edward’s tuberculosis is a death sentence.

Buchan finished the book just a few days before his own death from cerebral thrombosis. Then governor general of Canada, he had been a martyr to peptic ulcer for decades, and he eked out his …