Exit Music, Ian Rankin

It's late in the fall in Edinburgh and late in the career of Detective Inspector John Rebus. As he is simply trying to tie up some loose ends before his retirement, a new case lands on his desk: a dissident Russian poet has been murdered in what looks like a mugging gone wrong.
Rebus discovers that an elite delegation of Russian businessmen is in town, looking to expand its interests. And as Rebus's investigation gains ground, someone brutally assaults a local gangster with whom he has a long history.
Has Rebus overstepped his bounds for the last time? Only a few days shy of the end to his long, controversial career, will Rebus even make it that far?