Inspiration for my latest novel, ‘Pilgrim,’ came from a situation I encountered twenty-four years ago while I was a minister and missionary.

At the time of the incident in question, I was living and working at a combined mission station and plantation in the densely forested hills above Montego Bay, Jamaica. During the humid mid-summer heat, several staff fell sick with a curious, cold-like illness nobody seemed able to shake. Weeks dragged on with more falling ill. We were getting short-hand...