A call from an old friend brings back memories and more than a little guilt for DI John Rebus. Suddenly it seems Edinburgh's streets are crowded with the lost and forgotten.
Stalking a poisoner at the local zoo, Rebus hits upon a freed paedophile, camera in hand. Outing the man rouses the vigilantes and leaves Rebus with mixed feelings and another weight on his conscience. But then a convicted murderer is put under Rebus's watchful eye, looking to play games with Rebus as his pawn...