Wry and obsessive DI Buchan is a cop on the edge; suave and self-assured Jack Harvey is a best-selling crime novelist with the world at his feet. As Buchan probes a 100-year-old cold case, his investigation takes him on a journey into the Scottish capital's literary past that will cause him to question his very existence and set him on a collision course with his onetime friend. Written by James Mavor and based on an original idea by Ian Rankin, Reichenbach Falls (commissioned as part of BBC Four's fifth birthday celebrations) reflects Rankin's fascination with his home town of Edinburgh and the legacy of a city which has produced so many Scottish literary classics, from 'Kidnapped' to 'The 39 Steps', from 'Sherlock Holmes' to 'The Prime Of Miss Jean Brodie'.