I have read most of Lehane's novels. His treatment of the second book of the Coughlin family series is a departure from most of his Boston-set novels. It starts in Boston but winds up in FL and Cuba. It is one of his best writings -- full of surprises, wonderful turns of phrase, and penetrating insights. You won't regret reading it.
Boston, like Chicago, has a reputation for gangsters controlling many aspects of public life, including the politicians. This was especially true during Prohibition, when this novel takes place. If you like noir criminal fiction, this one's for you. Its 'hero' is the son of an honest police captain. But unlike his father, he opts for the lawless side of Law and Order.