Rebus is back on the force, albeit with a demotion and a chip on his shoulder. A 30-year-old case is being reopened, and Rebus's team from back then is suspected of foul play. With Malcolm Fox as the investigating officer, are the past and present about to collide in a shocking and murderous fashion? And does Rebus have anything to hide? His old colleagues called themselves 'the Saints', and swore a bond on something called 'the Shadow Bible'. But times have changed and the crimes of the past may not stay hidden much longer, especially with a referendum on Scottish independence just around the corner.

Who are the saints and who are the sinners? And can the one ever become the other?