Charles Macgregor is found dead in his house in Edinburgh, an apparent suicide. The Sheriff-Depute is left to examine a stack of letters that might reveal clues about the circumstance: the resulting epistolary tale reveals the tragic romance of Charles and Constance, as they fall in love, are forbidden to marry, run away to Gretna Green, are stopped, separated, brutalized, and Constance gradually comes to fall in love with another suitor.