Using a wide range of archival material, Plagues of the heart provides a fresh understanding of religion and identity not only in seventeenth-century Scotland, but in protestant communities across the early modern world grappling with a range of interrelated crises. By examining the 'culture of covenanting' in the southwestern port-city of Ayr between the British civil wars and the Revolution of 1688, this book reveals how adherence to the National Covenant of 1638 and the Solemn League and Covenant of 1643 informed the identities and lived experiences of a generation of Scots. This is the compelling story of one Scottish town and its remarkable minister, but it demonstrates how in the early modern period, especially when it came to matters of faith, the local was imbedded rather than isolated, engaged rather than insular.