Janus: Private Eyes by J.D. Blair

This is a collection of stories about a bent and disgraced San Francisco narcotics detective who was wrongly drummed off the force by fellow detectives Janus fingered for taking mob payoffs. Janus ends up on the streets of San Francisco, becomes homeless and addicted to drugs and alcohol. He has a run in with some toughs that brings him close to death and begins a turn around in his life. With the help of a former mentor Janus ultimately starts his own detective agency and takes on mob bosses and befriends a powerful political figure that more or less keeps Janus on a retainer. He becomes embroiled in cases of art theft, the murder of the son of a powerful San Francisco family and is nearly killed chasing a notorious Mexican drug lord. Janus is an old school detective fighting modern day crime. He is brash, witty and cunning. Is he dumb enough to enter the dark side? Of course he is.